Organometallic compound and organic light-emitting device including the same

ABSTRACT

An organometallic compound represented by Formula 1: 
       M(L 1 ) n1 (L 2 ) n2   Formula 1
 
     wherein in Formula 1, M, L 1 , L 2 , n1, and n2 are the same as described in the specification.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplications Nos. 10-2014-0169183, filed on Nov. 28, 2014, and10-2015-0129776, filed on Sep. 14, 2015, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND

1. Field

One or more embodiments relate to an organometallic compound and anorganic light-emitting device including the same.

2. Description of the Related Art

Organic light emitting devices (OLEDs) are self-emission devices thathave wide viewing angles, high contrast ratios, and short responsetimes. In addition, OLEDs exhibit excellent brightness, driving voltage,and response speed characteristics, and produce full-color images.

In an example, an organic light-emitting device includes an anode, acathode, and an organic layer that is disposed between the anode and thecathode and includes an emission layer. A hole transport region may bedisposed between the anode and the emission layer, and an electrontransport region may be disposed between the emission layer and thecathode. Holes provided from the anode may move toward the emissionlayer through the hole transport region, and electrons provided from thecathode may move toward the emission layer through the electrontransport region. The holes and the electrons are recombined in theemission layer to produce excitons. These excitons change from anexcited state to a ground state, thereby generating light.

Various types of organic light emitting devices are known. However,there still remains a need in OLEDs having low driving voltage, highefficiency, high brightness, and long lifespan.

SUMMARY

One or more embodiments relate to a novel organometallic compound and anorganic light-emitting device including the same.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

An aspect provides an organometallic compound represented by Formula 1:

wherein M in Formula 1 is selected from Ir, Pt, Os, Ti, Zr, Hf, Eu, Tb,Tm, and Rh,

in Formula 1, L₁ is a ligand represented by Formula 2A, n1 is 1, 2, or3, and when n1 is 2 or more, 2 or more L₁ may be identical or different,

in Formula 1, L₂ is selected from a monovalent organic ligand, adivalent organic ligand, a trivalent organic ligand, and a tetravalentorganic ligand, n2 is 0, 1, 2, 3, or 4, when n2 is 2 or more, 2 or moreL₂ may be identical or different,

L₁ and L₂ in Formula 1 may be different from each other,

R₁ to R₃ in Formula 2A may be each independently selected from asubstituted or unsubstituted C₁-C₆₀ alkyl group, a substituted orunsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstitutedC₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxygroup, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀aryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, a substituted or unsubstituted monovalent non-aromaticcondensed heteropolycyclic group, and —Si(Q₅₁)(Q₅₂)(Q₅₃),

X₁ in Formula 2A may be selected from O, S, S(═O)₂, N(R₂₁), andSi(R₂₂)(R₂₃),

in Formula 2A, Y₁ may be N, C(R₄₁) or a carbon atom connected to apyridine ring, Y₂ may be N, C(R₄₂) or a carbon atom connected to apyridine ring, Y₃ may be N, C(R₄₃) or a carbon atom connected to apyridine ring, Y₄ may be N, C(R₄₄) or a carbon atom connected to apyridine ring, Y₅ may be N or C(R₄₅), Y₆ may be N or C(R₄₆), Y₇ may be Nor C(R₄₇), Y₈ may be N or C(R₄₈), and one of Y₁ to Y₄ may be a carbonatom connected,

R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A may be each independentlyselected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, —SF₅, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroarylgroup, a substituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, a substituted or unsubstituted monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅),—B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), and 2 or more R₁₁ may optionally belinked to each other to form a saturated or unsaturated C₄-C₆₀ ring, andtwo or more of R₄₁ to R₄₄ may be optionally linked to each other to forma saturated or unsaturated C₄-C₆₀ ring, and two or more of R₄₅ to R₄₈may be optionally linked to each other to form a saturated orunsaturated C₄-C₆₀ ring,

in Formula 2A, b1 is an integer selected from 0 to 3, and b4 is aninteger selected from 1 to 4,

* and *′ in Formula 2A are binding sites to M in Formula 1,

at least one of substituents of the substituted C₁-C₆₀ alkyl group,substituted C₂-C₆₀ alkenyl group, substituted C₂-C₆₀ alkynyl group,substituted C₁-C₆₀ alkoxy group, substituted C₃-C₁₀ cycloalkyl group,substituted C₁-C₁₀ heterocycloalkyl group, substituted C₃-C₁₀cycloalkenyl group, substituted C₁-C₁₀ heterocycloalkenyl group,substituted C₆-C₆₀ aryl group, substituted C₆-C₆₀ aryloxy group,substituted C₆-C₆₀ arylthio group, substituted C₁-C₆₀ heteroaryl group,substituted monovalent non-aromatic condensed polycyclic group, andsubstituted monovalent non-aromatic condensed heteropolycyclic group isselected from

a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenylgroup, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group,and a C₁-C₆₀ alkoxy group, each substituted with at least one selectedfrom a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,—CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group,an amidino group, a hydrazine group, a hydrazone group, a carboxylicacid group or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, aC₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),—B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉);

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group;

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynylgroup, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉);

wherein Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, Q₃₁ to Q₃₉ and Q₅₁ to Q₅₃ maybe each independently selected from a hydrogen, a deuterium, —F, —Cl,—Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group,an amidino group, a hydrazine group, a hydrazone group, a carboxylicacid group or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a substituted or unsubstitutedC₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group,a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroarylgroup, a substituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, and a substituted or unsubstituted monovalentnon-aromatic condensed heteropolycyclic group.

Another aspect provides an organic light-emitting device including:

a first electrode;

a second electrode; and

an organic layer disposed between the first electrode and the secondelectrode, wherein the organic layer includes an emission layer and atleast one organometallic compound represented by Formula 1.

The emission layer may include the organometallic compound.

The organometallic compound included in the emission layer may act as adopant, and the emission layer may further include a host.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with

FIG. 1 which is a schematic view of an organic light-emitting deviceaccording to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the FIGURES, toexplain aspects of the present inventive concept. As used herein, theterm “and/or” includes any and all combinations of one or more of theassociated listed items. Expressions such as “at least one of,” whenpreceding a list of elements, modify the entire list of elements and donot modify the individual elements of the list.

It will be understood that when an element is referred to as being “on”another element, it can be directly in contact with the other element orintervening elements may be present therebetween. In contrast, when anelement is referred to as being “directly on” another element, there areno intervening elements present.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers, and/or sections, these elements, components, regions, layers,and/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer, orsection from another element, component, region, layer, or section.Thus, a first element, component, region, layer, or section discussedbelow could be termed a second element, component, region, layer, orsection without departing from the teachings of the present embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise.

It will be further understood that the terms “comprises” and/or“comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the FIGURES. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the FIGURES. For example, if the device in theFIGURES is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art an dthe present disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

An organometallic compound according to an embodiment is represented byFormula 1 below:

M(L₁)_(n1)(L₂)_(n2)  Formula 1

M in Formula 1 may be selected from iridium (Ir), platinum (Pt), osmium(Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu),terbium (Tb), thulium (Tm), and rhodium (Rh).

For example, M in Formula 1 may be selected from iridium (Ir), platinum(Pt), osmium (Os), and rhodium (Rh).

In some embodiments, M in Formula 1 may be selected from iridium (Ir)and platinum (Pt), but is not limited thereto.

In Formula 1, L₁ is a ligand represented by Formula 2A, n1 is 1, 2, or3, and when n1 is 2 or more, 2 or more L₁ may be identical or different.

wherein in Formula 1, L₂ is selected from a monovalent organic ligand, adivalent organic ligand, a trivalent organic ligand, and a tetravalentorganic ligand, n2 is 0, 1, 2, 3, or 4, when n2 is 2 or more, 2 or moreL₂ may be identical or different.

L₁ and L₂ in Formula 1 may be different from each other.

For example, n1 in Formula 1 may be 1.

In some embodiments, the organometallic compound represented by Formula1 may not include an ionic group. For example, the organometalliccompound may not be a salt consisting of an ionic pair.

In some embodiments, in Formula 1, M is Ir and the sum of n1 and n2 is3; or M is Pt and the sum of n1 and n2 is 2, and the organometalliccompound represented by Formula 1 may not include an ionic group.

R₁ to R₃ in Formula 2A may be each independently selected from asubstituted or unsubstituted C₁-C₆₀ alkyl group, a substituted orunsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstitutedC₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxygroup, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀aryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, a substituted or unsubstituted monovalent non-aromaticcondensed heteropolycyclic group, and —Si(Q₅₁)(Q₅₂)(Q₅₃).

For example, R₁ to R₃ in Formula 2A may be each independently selectedfrom a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, and—Si(Q₅₁)(Q₅₂)(Q₅₃);

a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolylgroup, a thiophenyl group, a furanyl group, an imidazolyl group, apyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolylgroup, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, apyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolylgroup, an indazolyl group, a purinyl group, a quinolinyl group, anisoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group; and

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolylgroup, a thiophenyl group, a furanyl group, an imidazolyl group, apyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolylgroup, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, apyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolylgroup, an indazolyl group, a purinyl group, a quinolinyl group, anisoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —OF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, abenzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinylgroup, and an imidazopyrimidinyl group; and

Q₅₁ to Q₅₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group, butembodiments are not limited thereto.

In other examples, R₁ to R₃ in Formula 2A may be each independentlyselected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, a naphthyl group, and —Si(Q₅₁)(Q₅₂)(Q₅₃); and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group;

Q₅₁ to Q₅₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group.

In some embodiments, Q₅₁ to Q₅₃ may be each independently a methyl groupor an ethyl group.

In some embodiments, in Formula 2A,

R₁ to R₃ may all be identical;

R₁ and R₃ may be identical and R₂ and R₁ may be different; or

R₁ to R₃ may all be different from each other.

X₁ in Formula 2A may be selected from O, S, S(═O)₂, N(R₂₁), andSi(R₂₂)(R₂₃).

For example, X₁ in Formula 2A may be selected from O, S, and N(R₂₁).

According to an embodiment, X₁ in Formula 2A may be 0, but is notlimited thereto.

R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A may be each independentlyselected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, —SF₅, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroarylgroup, a substituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, a substituted or unsubstituted monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅),—B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉).

For example, R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A may be eachindependently selected from

a hydrogen, a deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, acyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxygroup;

a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀alkyl group,

a C₁-C₁₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₁₄ aryl group, a C₁-C₁₄ heteroarylgroup, a monovalent non-aromatic condensed polycyclic group, and amonovalent non-aromatic condensed heteropolycyclic group;

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₁₄ arylgroup, a C₁-C₁₄ heteroaryl group, a monovalent non-aromatic condensedpolycyclic group, and a monovalent non-aromatic condensedheteropolycyclic group;

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₁₄ arylgroup, a C₁-C₁₄ heteroaryl group, a monovalent non-aromatic condensedpolycyclic group, and a monovalent non-aromatic condensedheteropolycyclic group, each substituted with at least one selected froma deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxygroup, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, aC₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₁₄aryl group, a C₁-C₁₄ heteroaryl group, a monovalent non-aromaticcondensed polycyclic group, and a monovalent non-aromatic condensedheteropolycyclic group; and

—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉);

Q₁ to Q₉ may be each independently selected from a substituted orunsubstituted C₁-C₂₀ alkyl group, a substituted or unsubstituted C₁-C₂₀alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₁₄ aryl group, a substituted or unsubstituted C₁-C₁₄heteroaryl group, a substituted or unsubstituted monovalent non-aromaticcondensed polycyclic group, and a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group.

In some embodiments, R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A may beeach independently selected from

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, —SF₅, a C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxy group;

a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolylgroup, a thiophenyl group, a furanyl group, an imidazolyl group, apyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolylgroup, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, apyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolylgroup, an indazolyl group, a purinyl group, a quinolinyl group, anisoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolylgroup, a thiophenyl group, a furanyl group, an imidazolyl group, apyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolylgroup, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, apyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolylgroup, an indazolyl group, a purinyl group, a quinolinyl group, anisoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, abenzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinylgroup, and an imidazopyrimidinyl group; and

—B(Q₆)(Q₇) and —P(═O)(Q₈)(Q₉),

Q₆ to Q₉ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group, butembodiments are not limited thereto.

In some embodiments, R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A may beeach independently selected from

a hydrogen, a deuterium, —F, a cyano group, a nitro group, —SF₅, amethyl group, an ethyl group, an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, an n-hexyl group, an isohexyl group, a sec-hexyl group, atert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptylgroup, a tert-heptyl group, an n-octyl group, an isooctyl group, asec-octyl group, a tert-octyl group, an n-nonyl group, an isononylgroup, a sec-nonyl group, a tert-nonyl group, an n-decyl group, anisodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group,an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl, norbornanyl group, a norbornenyl, a cyclopentenylgroup, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, anaphthyl group, a pyridinyl group, and a pyrimidinyl group;

a methyl group, an ethyl group, an n-propyl group, an isopropyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, an n-pentyl group, an isopentyl group, a sec-pentyl group, atert-pentyl group, an n-hexyl group, an isohexyl group, a sec-hexylgroup, a tert-hexyl group, an n-heptyl group, an isoheptyl group, asec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctylgroup, a sec-octyl group, a tert-octyl group, an n-nonyl group, anisononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group,an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxygroup, an ethoxy group, a propoxy group, a butoxy group, a pentoxygroup, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a pyridinyl group, and apyrimidinyl group, each substituted with at least one selected from adeuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, anitro group, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup; and

—B(Q₆)(Q₇) and —P(═O)(Q₈)(Q₉),

Q₆ to Q₉ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group.

In some embodiments, R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A may beeach independently selected from a hydrogen, a deuterium, —F, a cyanogroup, a nitro group, —SF₅, —CH₃, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,—CFH₂, groups represented by Formulae 9-1 to 9-17, and groupsrepresented by Formulae 10-1 to 10-30, but they are not limited thereto:

In Formulae 9-1 to 9-17 and to 10-1 to 10-30, * is a binding site to aneighboring atom.

In Formula 2A, b1 is an integer selected from 0 to 3, and b4 is aninteger selected from 1 to 4.

In some embodiments, R₂₁ to R₂₃ in X₁ of Formula 2A are eachindependently selected from

a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyridinyl group, apyrimidinyl group, and a triazinyl group;

a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, and a phosphoric acid group or a salt thereof;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyridinylgroup, a pyrimidinyl group, and a triazinyl group, each substituted withat least one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, and a naphthylgroup.

In Formula 2A, b1 indicates the number of R₁₁, when b1 is 2 or more, 2or more R₁₁ are identical or different, and b4 indicates the number of—Si(R₁)(R₂)(R₃), when b4 is 2 or more, 2 or more —Si(R₁)(R₂)(R₃) areidentical or different.

In some embodiments, in Formula 2A, b1 may be 0, 1 or 2, and b4 may be 1or 2, but they are not limited thereto.

In some embodiments, in Formula 2A, b1 may be 0 or 1, and b4 may be 1,but they are not limited thereto.

Regarding Formula 2A, two or more R₁₁s may be optionally linked to eachother to form a saturated or unsaturated C₄-C₆₀ ring (for example, acyclopentane, a cyclohexane, an adamantane, a norbornane, a benzene, apyridine, a pyrimidine, a naphthalene, a pyrene, or a chrysene), two ormore of R₄₁ to R₄₄ may be optionally linked to each other to form asaturated or unsaturated C₄-C₆₀ ring (for example, a cyclopentane, acyclohexane, an adamantane, a norbornane, a benzene, a pyridine, apyrimidine, a naphthalene, a pyrene, or a chrysene), and two or more ofR₄₅ to R₄₈ may be optionally linked to each other to form a saturated orunsaturated C₄-C₆₀ ring (for example, a cyclopentane, a cyclohexane, anadamantane, a norbornane, a benzene, a pyridine, a pyrimidine, anaphthalene, a pyrene, or a chrysene).

For example, two R₁₁s in Formula 2A may bind to each other to form asubstituted or unsubstituted a cyclohexane or a substituted orunsubstituted a benzene, but embodiments are not limited thereto.

In some embodiments, none of Y₁ to Y₈ in Formula 2A may be N.

In some embodiments, Y₁ or Y₃ in Formula 2A may be N.

In some embodiments, Y₅ or Y₆ in Formula 2A may be N.

In some embodiments, one or two of Y₁, Y₃, Y₅, and Y₆ in Formula 2A maybe N

In some embodiments, L₁ in Formula 1 may be selected from ligandsrepresented by Formula 2A-1 to 2A-16 below:

Regarding Formulae 2A-1 to 2A-16, descriptions of R₁ to R₃, X₁, Y₁ toY₈, R₁₁, b1 and b4 are the same as described above, descriptions of R₁₅are the same as described in connection with R₁₁, b5 is an integerselected from 0 to 8, and * and *′ are binding sites to M in Formula 1.

In some embodiments,

in Formulae 2A-1 to 2A-16, Y₁ may be C(R₄₁), Y₂ may be C(R₄₂), Y₃ may beC(R₄₃), Y₄ may be C(R₄₄), Y₅ may be C(R₄₅), Y₆ may be C(R₄₆), Y₇ may beC(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12,2A-13, 2A-14, and 2A-16, Y₁ may be N, Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12,2A-13, 2A-14, and 2A-16, Y₁ may be C(R₄₁), Y₄ may be C(R₄₄), Y₅ may beN, Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12,2A-13, 2A-14, and 2A-16, Y₁ may be C(R₄₁), Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12,2A-13, 2A-14, and 2A-16, Y₁ may be N, Y₄ may be C(R₄₄), Y₅ may be N, Y₆may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12,2A-13, 2A-14, and 2A-16, Y₁ may be N, Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A-3, 2A-7, 2A-11, and 2A-15, Y₃ may be N, Y₄ may be C(R₄₄),Y₅ may be C(R₄₅), Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may beC(R₄₈);

in Formulae 2A-3, 2A-7, 2A-11, and 2A-15, Y₃ may be C(R₄₃), Y₄ may beC(R₄₄), Y₅ may be N, Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may beC(R₄₈);

in Formulae 2A-3, 2A-7, 2A-11, and 2A-15, Y₃ may be C(R₄₃), Y₄ may beC(R₄₄), Y₅ may be C(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may beC(R₄₈);

in Formulae 2A-3, 2A-7, 2A-11, and 2A-15, Y₃ may be N, Y₄ may be C(R₄₄),Y₅ may be N, Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A-3, 2A-7, 2A-11, and 2A-15, Y₃ may be N, Y₄ may be C(R₄₄),Y₅ may be C(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈),but they are not limited thereto.

In this regard, a maximum luminance wavelength decreases in thisfollowing order: i) an organometallic compound using the ligandrepresented by Formula 2A-4, 2A-8, 2A-12 or 2A-16 ii) an organometalliccompound using the ligand represented by Formula 2A-2, 2A-6, 2A-10 or2A-14 iii) an organometallic compound using the ligand represented byFormula 2A-3, 2A-7, 2A-11 or 2A-15 and iv) an organometallic compoundusing the ligand represented by Formula 2A-1, 2A-5, 2A-9 or 2A-13. Thatis, a maximum luminance wavelength of the organometallic compound usingthe ligand represented by Formula 2A-1, 2A-5, 2A-9 or 2A-13 amongFormulae 2A-1 to 2A-16 is the smallest.

In some embodiments, L₁ in Formula 1 may be selected from ligandsrepresented by Formulae 2AA-1, 2AA-2, 2AA-3, 2AA-4 and 2AB below. WhenL₁ in Formula 1 is selected from ligands represented by Formulae 2AA-1and 2AB, an organic light-emitting device using the organometalliccompound represented by Formula 1 may have high efficiency and a longlife span.

Regarding Formulae 2AA-1, 2AA-2, 2AA-3, 2AA-4, and 2AB, R₁ to R₃, X₁, Y₁to Y₈, R₁₁, and b1 are already described above, R₁₅ may be understood byreferring to the description of R₁₁, b5 is an integer selected from 0 to8, and each of * and *′ indicates a binding site to M in Formula 1.

For example, in Formulae 2A-1 to 2A-16, 2AA-1, 2AA-2, 2AA-3, 2AA-4, and2AB,

R₁ to R₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, a naphthyl group, and —Si(Q₅₁)(Q₅₂)(Q₅₃); and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group;

Q₅₁ to Q₅₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group,

X₁ may be selected from O, S, S(═O)₂, N(R₂₁), and Si(R₂₂)(R₂₃),

Y₁ to Y₈ are already described above,

R₁₁, R₁₅, R₂₁ to R₂₃ and R₄₁ to R₄₈ may be each independently selectedfrom

a hydrogen, a deuterium, —F, a cyano group, a nitro group, —SF₅, amethyl group, an ethyl group, an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, an n-hexyl group, an isohexyl group, a sec-hexyl group, atert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptylgroup, a tert-heptyl group, an n-octyl group, an isooctyl group, asec-octyl group, a tert-octyl group, an n-nonyl group, an isononylgroup, a sec-nonyl group, a tert-nonyl group, an n-decyl group, anisodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group,an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl, norbornanyl group, a norbornenyl, a cyclopentenylgroup, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, anaphthyl group, a pyridinyl group, and a pyrimidinyl group;

a methyl group, an ethyl group, an n-propyl group, an isopropyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, an n-pentyl group, an isopentyl group, a sec-pentyl group, atert-pentyl group, an n-hexyl group, an isohexyl group, a sec-hexylgroup, a tert-hexyl group, an n-heptyl group, an isoheptyl group, asec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctylgroup, a sec-octyl group, a tert-octyl group, an n-nonyl group, anisononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group,an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxygroup, an ethoxy group, a propoxy group, a butoxy group, a pentoxygroup, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a pyridinyl group, and apyrimidinyl group, each substituted with at least one selected from adeuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, anitro group, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup; and

—B(Q₆)(Q₇) and —P(═O)(Q₈)(Q₉),

Q₆ to Q₉ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, and a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium and a C₁-C₁₀ alkyl group,

b1 may be an integer selected from 0 to 3,

b4 may be 1 or 2,

b5 may be an integer selected from 0 to 8, but they are not limitedthereto.

In some embodiments, L₁ in Formula 1 may be selected from ligandsrepresented by Formulae 2A(1) to 2A(40) below:

Regarding Formulae 2A(1) to 2A(40), R₁ to R₃, X₁, Y₁ to Y₈, and R₁₁ arealready described above, R_(11a) and R_(11b) may be understood byreferring to the description of R₁₁, and each of * and *′ indicates abinding site to M in Formula 1, provided that R₁₁, R_(11a), and R_(11b)are not hydrogen.

In some embodiments,

in Formulae 2A(1) to 2A(40), Y₁ may be C(R₄₁), Y₂ may be C(R₄₂), Y₃ maybe C(R₄₃), Y₄ may be C(R₄₄), Y₅ may be C(R₄₅), Y₆ may be C(R₄₆), Y₇ maybe C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(1) to 2(4), 2A(7) to 2A(12), 2A(15) to 2A(20), 2A(23) to2A(28), and 2A(31) to 2A(36), Y₁ may be N, Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(1) to 2(4), 2A(7) to 2A(12), 2A(15) to 2A(20), 2A(23) to2A(28), and 2A(31) to 2A(36), Y₁ may be C(R₄₁), Y₄ may be C(R₄₄), Y₅ maybe N, Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(1) to 2(4), 2A(7) to 2A(12), 2A(15) to 2A(20), 2A(23) to2A(28), and 2A(31) to 2A(36), Y₁ may be C(R₄₁), Y₄ may be C(R₄₄), Y₅ maybe C(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(1) to 2(4), 2A(7) to 2A(12), 2A(15) to 2A(20), 2A(23) to2A(28), and 2A(31) to 2A(36), Y₁ may be N, Y₄ may be C(R₄₄), Y₅ may beN, Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(1) to 2(4), 2A(7) to 2A(12), 2A(15) to 2A(20), 2A(23) to2A(28), and 2A(31) to 2A(36), Y₁ may be N, Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(5), 2A(6), 2A(13), 2A(14), 2A(21), 2A(22), 2A(29),2A(30), 2A(37), and 2A(38), Y₃ may be N, Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formula 2A(5), 2A(6), 2A(13), 2A(14), 2A(21), 2A(22), 2A(29), 2A(30),2A(37), and 2A(38), Y₃ may be C(R₄₃), Y₄ may be C(R₄₄), Y₅ may be N, Y₆may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(5), 2A(6), 2A(13), 2A(14), 2A(21), 2A(22), 2A(29),2A(30), 2A(37), 2A(38), Y₃ may be C(R₄₃), Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈);

in Formulae 2A(5), 2A(6), 2A(13), 2A(14), 2A(21), 2A(22), 2A(29),2A(30), 2A(37), and 2A(38), Y₃ may be N, Y₄ may be C(R₄₄), Y₅ may be N,Y₆ may be C(R₄₆), Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈); or

in Formulae 2A(5), 2A(6), 2A(13), 2A(14), 2A(21), 2A(22), 2A(29),2A(30), 2A(37), and 2A(38), Y₃ may be N, Y₄ may be C(R₄₄), Y₅ may beC(R₄₅), Y₆ may be N, Y₇ may be C(R₄₇), and Y₈ may be C(R₄₈), but theyare not limited thereto.

For example, in Formulae 2A(1) to 2A(40),

R₁ to R₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, a naphthyl group, and —Si(Q₅₁)(Q₅₂)(Q₅₃); and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group;

Q₅₁ to Q₅₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group,

X₁ may be selected from O, S, S(═O)₂, N(R₂₁), and Si(R₂₂)(R₂₃),

Y₁ to Y₈ are already described above,

R₁₁, R_(11a), R_(11b), R₂₁ to R₂₃ and R₄₁ to R₄₈ are each independentlyselected from

a hydrogen, a deuterium, —F, a cyano group, a nitro group, —SF₅, amethyl group, an ethyl group, an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, an n-hexyl group, an isohexyl group, a sec-hexyl group, atert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptylgroup, a tert-heptyl group, an n-octyl group, an isooctyl group, asec-octyl group, a tert-octyl group, an n-nonyl group, an isononylgroup, a sec-nonyl group, a tert-nonyl group, an n-decyl group, anisodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group,an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl, norbornanyl group, a norbornenyl, a cyclopentenylgroup, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, anaphthyl group, a pyridinyl group, and a pyrimidinyl group;

a methyl group, an ethyl group, an n-propyl group, an isopropyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, an n-pentyl group, an isopentyl group, a sec-pentyl group, atert-pentyl group, an n-hexyl group, an isohexyl group, a sec-hexylgroup, a tert-hexyl group, an n-heptyl group, an isoheptyl group, asec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctylgroup, a sec-octyl group, a tert-octyl group, an n-nonyl group, anisononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group,an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxygroup, an ethoxy group, a propoxy group, a butoxy group, a pentoxygroup, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a pyridinyl group, and apyrimidinyl group, each substituted with at least one selected from adeuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, anitro group, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup; and

—B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉) (provided that, R₁₁, R_(11a), and R_(11b)in Formulae 2A(1) to 2A(40) is not a hydrogen), Q₆ to Q₉ may be eachindependently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium and a C₁-C₁₀ alkyl group, but embodiments are notlimited thereto.

In some embodiments, regarding Formulae 2A(1) to 2A(40),

R₁ to R₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, a naphthyl group, and —Si(Q₅₁)(Q₅₂)(Q₅₃); and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group;

Q₅₁ to Q₅₃ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group,

X₁ may be selected from O, S, S(═O)₂, N(R₂₁), and Si(R₂₂)(R₂₃),

Y₁ to Y₈ are already described above,

R₁₁, R_(11a), R_(1b) and R₄₁ to R₄₈ may be selected from a deuterium,—F, a cyano group, a nitro group, —SF₅, —CH₃, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, groups represented by Formulae 9-1 to 9-17, and groupsrepresented by Formulae 10-1 to 10-30,

R₂₁ to R₂₃ are each independently selected from

a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyridinyl group, apyrimidinyl group, and a triazinyl group;

a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, and a phosphoric acid group or a salt thereof; and

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyridinylgroup, a pyrimidinyl group, and a triazinyl group, each substituted withat least one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, and a naphthylgroup,

but are not limited thereto.

L₂ in Formula 1 may be selected from ligands represented by Formulae 3Ato 3G:

wherein in Formulae 3A to 3G,

Y₁₁ to Y₁₆ are each independently carbon (C) or nitrogen (N), Y₁₁ andY₁₂ are linked to each other by a single bond or a double bond, Y₁₃ andY₁₄ are linked to each other by a single bond or a double bond, and Y₁₅and Y₁₆ are linked to each other by a single bond or a double bond,

CY₃ to CY₅ are each independently selected from a C₅-C₆₀ carbocyclicgroup and a C₂-C₆₀ heterocyclic group (“a monocyclic group” or“polycyclic group”, respectively).

a1 to a3 are each independently an integer selected from 1 to 5 and CY₃and CY₄ may be optionally additionally linked to each other via anorganic linking group,

A₁ is P or As;

X_(11a), X_(11b), X_(12a), X_(12b), X_(13a), and X_(13b) may be eachindependently selected from N, O, N(R₃₄), P(R₃₅)(R₃₆), and As(R₃₇)(R₃₈)(provided that none of X_(12a), X_(12b), X_(13a), and X_(13b) are N orO);

R_(33″) and R_(34″) are each independently selected from a single bond,a double bond, a substituted or unsubstituted C₁-C₅ alkylene group, asubstituted or unsubstituted C₂-C₅ alkenylene group, and a substitutedor unsubstituted C₆-C₁₀ arylene group;

Z₁ to Z₃, R₃₁, R_(32a), R_(32b), R_(32c), R_(33a), R_(33b), R₃₄ to R₃₈,R_(35a), R_(35b), R_(35c), and R_(35d) are each independently selectedfrom a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, acyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkylgroup, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroarylgroup, a substituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, a substituted or unsubstituted monovalent non-aromaticcondensed heteropolycyclic group,

—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉),

* and *′ each indicate binding sites to M in Formula 1;

at least one of substituents of the substituted C₁-C₅ alkylene group,substituted C₂-C₅ alkenylene group, substituted C₆-C₁₀ arylene group,substituted C₁-C₆₀ alkyl group, substituted C₂-C₆₀ alkenyl group,substituted C₂-C₆₀ alkynyl group, substituted C₁-C₆₀ alkoxy group,substituted C₃-C₁₀ cycloalkyl group, substituted C₁-C₁₀ heterocycloalkylgroup, substituted C₃-C₁₀ cycloalkenyl group, substituted C₁-C₁₀heterocycloalkenyl group, substituted C₆-C₆₀ aryl group, substitutedC₆-C₆₀ aryloxy group, substituted C₆-C₆₀ arylthio group, substitutedC₁-C₆₀ heteroaryl group, substituted monovalent non-aromatic condensedpolycyclic group and substituted monovalent non-aromatic condensedheteropolycyclic group is selected from

a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenylgroup, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group,and a C₁-C₆₀ alkoxy group, each substituted with at least one selectedfrom a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,—CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group,an amidino group, a hydrazine group, a hydrazone group, a carboxylicacid group or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, aC₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),—B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉);

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group;

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynylgroup, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉);

wherein Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ may be eachindependently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroarylgroup, a substituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, and a substituted or unsubstituted monovalentnon-aromatic condensed heteropolycyclic group.

According to an embodiment, CY₃ to CY₅ in Formulae 3A and 3B may be eachindependently selected from a benzene, a naphthalene, a fluorene, aspiro-fluorene, an indene, a pyrrole, a thiophene, a furan, animidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, anisoxazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, aquinoline, an isoquinoline, a benzoquinoline, a quinoxaline, aquinazoline, a carbazole, a benzoimidazole, a benzofuran, abenzothiophene, an isobenzothiophene, a benzoxazole, an isobenzoxazole,a triazole, a tetrazole, an oxadiazole, a triazine, a dibenzofuran, adibenzothiophene, and 5,6,7,8-tetrahydroisoquinoline, but they are notlimited thereto.

In some embodiments, L₂ in Formula 1 may be selected from ligandsrepresented by Formulae 3-1 to 3-111, but are not limited thereto:

wherein in Formulae 3-1 to 3-111,

Z₁, Z₂, Z_(1a), Z_(1b), Z_(2a), Z_(2b), Z_(2c), R_(34a), R_(34b), andR_(34c) may be each independently selected from

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, —SF₅, a C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxy group;

a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolylgroup, a thiophenyl group, a furanyl group, an imidazolyl group, apyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolylgroup, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, apyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolylgroup, an indazolyl group, a purinyl group, a quinolinyl group, anisoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolylgroup, a thiophenyl group, a furanyl group, an imidazolyl group, apyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolylgroup, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, apyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolylgroup, an indazolyl group, a purinyl group, a quinolinyl group, anisoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —OF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, abenzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinylgroup, and an imidazopyrimidinyl group; and

—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉);

Q₁ to Q₉ and Q₄₄ to Q₄₉ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, and a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium and a C₁-C₁₀ alkyl group,

aa2 and ab2 are each independently 1 or 2,

aa3 and ab3 are each independently selected from 1, 2, and 3,

aa4 and ab4 may be each independently selected from, 1, 2, 3, and 4, and

* and *′ each indicate binding sites to M in Formula 1.

Z₁, Z₂, Z_(1a), Z_(1b), Z_(2a), Z_(2b), Z_(2c), R_(34a), R_(34b), andR_(34c) in Formulae 3-1 to 3-111 may be each independently selected from

a hydrogen, a deuterium, —F, a cyano group, a nitro group, —SF₅, amethyl group, an ethyl group, an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, an n-hexyl group, an isohexyl group, a sec-hexyl group, atert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptylgroup, a tert-heptyl group, an n-octyl group, an isooctyl group, asec-octyl group, a tert-octyl group, an n-nonyl group, an isononylgroup, a sec-nonyl group, a tert-nonyl group, an n-decyl group, anisodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group,an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl, norbornanyl group, a norbornenyl, a cyclopentenylgroup, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, anaphthyl group, a pyridinyl group, and a pyrimidinyl group;

a methyl group, an ethyl group, an n-propyl group, an isopropyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, an n-pentyl group, an isopentyl group, a sec-pentyl group, atert-pentyl group, an n-hexyl group, an isohexyl group, a sec-hexylgroup, a tert-hexyl group, an n-heptyl group, an isoheptyl group, asec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctylgroup, a sec-octyl group, a tert-octyl group, an n-nonyl group, anisononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group,an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxygroup, an ethoxy group, a propoxy group, a butoxy group, a pentoxygroup, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a pyridinyl group, and apyrimidinyl group, each substituted with at least one selected from adeuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, anitro group, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup;

—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉);

Q₁ to Q₉ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium and a C₁-C₁₀ alkyl group, but embodiments are notlimited thereto.

In some embodiments, L₂ in Formula 1 may be selected from ligandsrepresented by Formulae 3-1(1) to 3-1(59) below and Formula 3-111 above:

For example, in Formulae 3-1(1)to 3-1(59) and Formula 3-111:

Z₁, Z₂, Z_(1a), Z_(1b), Z_(1c), Z_(1d), Z_(2a), Z_(2b), Z_(2c), Z_(2d),R_(34a), R_(34b), and R_(34c) are each independently selected from adeuterium, —F, a cyano group, a nitro group, —SF₅, —CH₃, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, —Si(Q₃)(Q₄)(Q₅), groups represented byFormulae 9-1 to 9-17, and groups represented by Formulae 10-1 to 10-30,

Q₃ to Q₅ may be each independently selected from

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂;

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group; and

an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, an n-pentyl group, anisopentyl group, a sec-pentyl group, a tert-pentyl group, a phenylgroup, and a naphthyl group, each substituted with at least one selectedfrom a deuterium and a C₁-C₁₀ alkyl group, and

* and *′ are binding sites to M in Formula 1.

In some embodiments, in Formula 1, M is Ir and the sum of n1 and n2 is3; or M is Pt and the sum of n1 and n2 is 2,

the organometallic compound represented by Formula 1 does not include anionic group, and

L₁ in Formula 1 may be selected from ligands represented by Formulae2A-1 to 2A-16, 2AA-1, 2AA-2, 2AA-3, 2AA-4, and 2AB, but embodiments arenot limited thereto.

In some embodiments, in Formula 1, M is Ir and the sum of n1 and n2 is3; or M is Pt and the sum of n1 and n2 is 2,

the organometallic compound represented by Formula 1 does not include anionic group,

L₁ in Formula 1 is selected from ligands represented by Formulae 2A-1,2A-5, 2AA-1 and 2AB, but embodiments are not limited thereto.

In some embodiments, in Formula 1, M is Ir and the sum of n1 and n2 is3; or M is Pt and the sum of n1 and n2 is 2, the organometallic compoundrepresented by Formula 1 is neutral, L₁ in Formula 1 is selected fromligands represented by Formulae 2A-1, 2A-5, 2AA-1, and 2AB, L₂ inFormula 1 is selected from ligands represented by Formulae 3-1 to 3-111(for example, ligands represented by Formulae 3-1(1) to 3-1(59) and3-111), but embodiments are not limited thereto.

In some embodiments, in Formula 1, M is Ir and the sum of n1 and n2 is3; or M is Pt and the sum of n1 and n2 is 2,

the organometallic compound represented by Formula 1 does not include anionic group, and

L₁ in Formula 1 is selected from ligands represented by Formulae 2A(1)to 2A(40), but embodiments are not limited thereto.

In some embodiments, in Formula 1, M is Ir and the sum of n1 and n2 is3; or M is Pt and the sum of n1 and n2 is 2,

the organometallic compound represented by Formula 1 does not include anionic group,

L₁ in Formula 1 is selected from ligands represented by Formulae 2A(1)to 2A(40), and

L₂ in Formula 1 is selected from ligands represented by Formulae 3-1 to3-111 (for example, ligands represented by Formulae 3-1(1) to 3-1(59)and 3-111), but embodiments are not limited thereto

For example, the organometallic compound represented by Formula 1 may beone of Compounds 1 to 481 below, but is not limited thereto.

Regarding the organometallic compound represented by Formula 1, L₁ isselected from a ligand represented by Formula 2A, and b4 in Formula 2Ais 1 or more. That is, a substituent of a pyridine-based ring in Formula2A may include at least one group —Si(R₁)(R₂)(R₃). Group —Si(R₁)(R₂)(R₃)increases spin density of metal M in Formula 1. Accordingly, an organiclight-emitting device using the organometallic compound represented byFormula 1 having the ligand represented by Formula 2A may have highefficiency.

Also, X₁ in Formula 2A may be selected from O, S, S(═O)₂, N(R₂₁), andSi(R₂₂)(R₂₃). When X₁ is selected from the groups above, charge mobilityof the organometallic compound represented by Formula 1 having theligand represented by Formula 2A improves, and energy levels thereof areeasily controllable. Accordingly, efficiency and lifespan of an organiclight-emitting device using the organometallic compound may be improved.

For example, HOMO, LUMO, singlet (Si) and triplet (Ti) energy levels ofthe organometallic compounds 1, 2, 8, 22, 139, 146, 304, 305, 321, 323,327 and 419 were evaluated by using a DFT method of Gaussian program(structurally optimized at a level of B3LYP, 6-31G(d,p)). Evaluationresults are shown in Table 1 below.

TABLE 1 S₁ energy T₁ energy level Compound No. HOMO(eV) LUMO(eV) level(eV) (eV) Compound 1 −4.842 −1.262 2.887 2.616 Compound 2 −4.874 −1.3092.869 2.591 Compound 8 −4.812 −1.249 2.875 2.608 Compound 22 −4.812−1.250 2.889 2.633 Compound 139 −4.827 −1.283 2.867 2.589 Compound 146−4.829 −1.261 2.872 2.510 Compound 304 −4.781 −1.267 2.837 2.586Compound 305 −4.773 −1.244 2.852 2.600 Compound 321 −4.856 −1.369 2.8032.555 Compound 323 −4.820 −1.281 2.849 2.591 Compound 327 −4.863 −1.3042.887 2.614 Compound 419 −4.756 −1.331 2.753 2.525

From Table 1, it is confirmed that the organometallic compoundrepresented by Formula 1 has electric characteristics that are suitablefor use as a material for manufacturing a device, for example, anorganic light-emitting device.

Synthesis methods of the organometallic compound represented by Formula1 may be recognizable by one of ordinary skill in the art by referringto Synthesis Examples provided below.

The organometallic compound represented by Formula 1 is suitable for usein an organic layer of an organic light-emitting device, for example,for use as a dopant in an emission layer of the organic layer. Thus,another aspect provides an organic light-emitting device that includes:

a first electrode;

a second electrode; and

an organic layer disposed between the first electrode and the secondelectrode, wherein the organic layer includes an emission layer and atleast one organometallic compound represented by Formula 1.

The organic light-emitting device may have, due to the inclusion of anorganic layer including the organometallic compound represented byFormula 1, a low driving voltage, high efficiency, high power, and along lifespan.

The organometallic compound of Formula 1 may be used between a pair ofelectrodes of an organic light-emitting device. For example, theorganometallic compound represented by Formula 1 may be included in theemission layer. In this regard, the organometallic compound may act as adopant, and the emission layer may further include a host (that is, anamount of the organometallic compound represented by Formula 1 issmaller than an amount of the host).

The expression “(an organic layer) includes at least one organometalliccompounds” used herein may include an embodiment in which (an organiclayer) includes identical organometallic compounds of Formula 1 and anembodiment in which (an organic layer) includes two or more differentorganometallic compounds of Formula 1.

For example, the organic layer may include, as the organometalliccompound, only Compound 1. In this regard, Compound 1 may be included inan emission layer of the organic light-emitting device. In someembodiments, the organic layer may include, as the organometalliccompound, Compound 1 and Compound 2. In this regard, Compound 1 andCompound 2 may be included in an identical layer (for example, Compound1 and Compound 2 all may be included in an emission layer).

The first electrode may be an anode, which is a hole injectionelectrode, and the second electrode may be a cathode, which is anelectron injection electrode; or the first electrode may be a cathode,which is an electron injection electrode, and the second electrode maybe an anode, which is a hole injection electrode.

For example, the first electrode is an anode, and the second electrodeis a cathode, and the organic layer includes i) a hole transport regionbetween the first electrode and the emission layer, and ii) an electrontransport region between the emission layer and the second electrode,and the hole transport region includes at least one selected from a holeinjection layer, a hole transport layer, and an electron blocking layer,and the electron transport region includes at least one selected from ahole blocking layer, an electron transport layer, and an electroninjection layer.

The term “organic layer” as used herein refers to a single layer and/ora plurality of layers disposed between the first electrode and thesecond electrode of an organic light-emitting device. The “organiclayer” may include, in addition to an organic compound, anorganometallic complex including metal.

FIG. 1 is a schematic view of an organic light-emitting device 10according to an embodiment. Hereinafter, the structure of an organiclight-emitting device according to an embodiment and a method ofmanufacturing an organic light-emitting device according to anembodiment will be described in connection with FIG. 1. The organiclight-emitting device 10 includes a first electrode 11, an organic layer15, and a second electrode 19, which are sequentially stacked.

In FIG. 1, a substrate may be additionally disposed under the firstelectrode 11 or above the second electrode 19. As the substrate, anysubstrate that is used in general organic light-emitting devices may beused. The substrate may be a glass substrate or transparent plasticsubstrate, each with excellent mechanical strength, thermal stability,transparency, surface smoothness, ease of handling, andwater-resistance.

The first electrode 11 may be formed by depositing or sputtering amaterial for forming the first electrode on the substrate. The firstelectrode 11 may be an anode. The material for the first electrode 11may be selected from materials with a high work function to allow holesbe easily provided. The first electrode 11 may be a reflective electrodeor a transmissive electrode. The material for the first electrode maybe, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tinoxide (SnO₂), and zinc oxide (ZnO). In some embodiments, magnesium (Mg),aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium(Mg—In), or magnesium-silver (Mg—Ag) may be used as the material for thefirst electrode.

The first electrode 11 may have a single-layer structure or amulti-layer structure including two or more layers. For example, thefirst electrode 11 may have a three-layered structure of ITO/Ag/ITO, butthe structure of the first electrode 11 is not limited thereto.

An organic layer 15 is disposed on the first electrode 11.

The organic layer 15 may include a hole transport region, an emissionlayer, and an electron transport region.

The hole transport region may be disposed between the first electrode 11and the emission layer.

The hole transport region may include at least one selected from a holeinjection layer, a hole transport layer, an electron blocking layer, anda buffer layer.

The hole transport region may include only either a hole injection layeror a hole transport layer. In some embodiments, the hole transportregion may have a structure of hole injection layer/hole transport layeror hole injection layer/hole transport layer/electron blocking layer,which are sequentially stacked in this stated order from the firstelectrode 11.

A hole injection layer may be formed on the first electrode 11 by usingvarious methods, such as vacuum deposition, spin coating, casting, orLangmuir-Blodgett (LB).

When a hole injection layer is formed by vacuum deposition, thedeposition conditions may vary according to a material that is used toform the hole injection layer, and the structure and thermalcharacteristics of the hole injection layer. For example, the depositionconditions may include a deposition temperature of about 100 to about500° C., a vacuum pressure of about 10⁻⁸ to about 10⁻³ torr, and adeposition rate of about 0.01 to about 100 Angstroms per second (A/sec).However, the deposition conditions are not limited thereto.

When the hole injection layer is formed using spin coating, coatingconditions may vary according to the material used to form the holeinjection layer, and the structure and thermal properties of the holeinjection layer. For example, a coating speed may be from about 2,000revolutions per minute (rpm) to about 5,000 rpm, and a temperature atwhich a heat treatment is performed to remove a solvent after coatingmay be from about 80° C. to about 200° C. However, the coatingconditions are not limited thereto.

Conditions for a hole transport layer and an electron blocking layer maybe understood by referring to conditions for forming the hole injectionlayer.

The hole transport region may include at least one selected fromm-MTDATA, TDATA, 2-TNATA, NPB, β-NPB, TPD, Spiro-TPD, Spiro-NPB,methylated NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine(TCTA), polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS),polyaniline/camphor sulfonic acid (PANI/CSA),(polyaniline)/poly(4-styrenesulfonate) (Pani/PSS), a compoundrepresented by Formula 201 below, and a compound represented by Formula202 below:

Ar₁₀₁ to Ar₁₀₂ in Formula 201 may be each independently selected from

a phenylene group, a pentalenylene group, an indenylene group, anaphthylene group, an azulenylene group, a heptalenylene group, anacenaphthylene group, a fluorenylene group, a phenalenylene group, aphenanthrenylene group, an anthracenylene group, a fluoranthenylenegroup, a triphenylenylene group, a pyrenylene group, a chrysenylenylenegroup, a naphthacenylene group, a picenylene group, a perylenylenegroup, and a pentacenylene group; and

a phenylene group, a pentalenylene group, an indenylene group, anaphthylene group, an azulenylene group, a heptalenylene group, anacenaphthylene group, a fluorenylene group, a phenalenylene group, aphenanthrenylene group, an anthracenylene group, a fluoranthenylenegroup, a triphenylenylene group, a pyrenylene group, a chrysenylenylenegroup, a naphthacenylene group, a picenylene group, a perylenylenegroup, and a pentacenylene group, each substituted with at least oneselected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynylgroup, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, and a monovalent non-aromaticcondensed heteropolycyclic group.

In Formula 201, xa and xb may be each independently an integer of 0 to5, or 0, 1, or 2. For example, xa is 1 and xb is 0, but xa and xb arenot limited thereto.

R₁₀₁ to R₁₀₈, R₁₁₁ to R₁₁₉ and R₁₂₁ to R₁₂₄ in Formulae 201 and 202 maybe each independently selected from

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₁₀ alkyl group (for example, a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group, a hexyl group, andso on), or a C₁-C₁₀ alkoxy group (for example, a methoxy group, anethoxy group, a propoxy group, a butoxy group, a pentoxy group, and soon);

a C₁-C₁₀ alkyl group or a C₁-C₁₀alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group,a cyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, and a phosphoric acidgroup or a salt thereof;

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenylgroup, and a pyrenyl group; and

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenylgroup, and a pyrenyl group, each substituted with at least one selectedfrom deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, anitro group, an amino group, an amidino group, a hydrazine group, ahydrazone group, a carboxylic acid group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,a C₁-C₁₀ alkyl group, and a C₁-C₁₀ alkoxy group, but they are notlimited thereto.

R₁₀₉ in Formula 201 may be selected from

a phenyl group, a naphthyl group, an anthracenyl group and a pyridinylgroup; and

a phenyl group, a naphthyl group, an anthracenyl group and a pyridinylgroup, each substituted with at least one selected from a deuterium, —F,—Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an aminogroup, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkylgroup, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, ananthracenyl group, and a pyridinyl group.

According to an embodiment, the compound represented by Formula 201 maybe represented by Formula 201A, but is not limited thereto:

R₁₀₁, R₁₁₁, R₁₁₂, and R₁₀₉ in Formula 201A may be understood byreferring to the description provided herein.

For example, the compound represented by Formula 201, and the compoundrepresented by Formula 202 may include compounds HT1 to HT20 illustratedbelow, but are not limited thereto.

A thickness of the hole transport region may be in a range of about 100Angstroms (Å) to about 10,000 Å, for example, about 100 Å to about 1,000Å. When the hole transport region includes a hole injection layer and ahole transport layer, the thickness of the hole injection layer may bein a range of about 100 Å to about 10,000 Å, and for example, about 100Å to about 1,000 Å, and the thickness of the hole transport layer may bein a range of about 50 Å to about 2,000 Å, and for example, about 100 Åto about 1,500 Å. When the thicknesses of the hole transport region, thehole injection layer, and the hole transport layer are within theseranges, satisfactory hole transporting characteristics may be obtainedwithout a substantial increase in driving voltage.

The hole transport region may further include, in addition to thesematerials, a charge-generation material for the improvement ofconductive properties. The charge-generation material may behomogeneously or non-homogeneously dispersed in the hole transportregion.

The charge-generation material may be, for example, a p-dopant. Thep-dopant may be one selected from a quinone derivative, a metal oxide,and a cyano group-containing compound, but embodiments are not limitedthereto. Non-limiting examples of the p-dopant are a quinone derivative,such as tetracyanoquinonedimethane (TCNQ) or2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ); ametal oxide, such as a tungsten oxide or a molybdenium oxide; and acyano group-containing compound, such as Compound HT-D1 below, but arenot limited thereto.

The hole transport region may include a buffer layer.

Also, the buffer layer may compensate for an optical resonance distanceaccording to a wavelength of light emitted from the emission layer, andthus, efficiency of a formed organic light-emitting device may beimproved.

Then, an emission layer (EML) may be formed on the hole transport regionby vacuum deposition, spin coating, casting, LB deposition, or the like.When the emission layer is formed by vacuum deposition or spin coating,the deposition or coating conditions may be similar to those applied toform the hole injection layer, although the deposition or coatingconditions may vary according to the material that is used to form theemission layer.

Meanwhile, when the hole transport region includes an electron blockinglayer, a material for the electron blocking layer may be selected frommaterials for the hole transport region described above and materialsfor a host to be explained later. However, the material for the electronblocking layer is not limited thereto. For example, when the holetransport region includes an electron blocking layer, a material for theelectron blocking layer may be mCP, which will be explained below.

The emission layer may include a host and a dopant, and the dopant mayinclude the organometallic compound represented by Formula 1.

The host may include at least one selected form TPBi, TBADN, ADN (alsoreferred to as “DNA”), CBP, CDBP, TCP, mCP, Compound H50, and CompoundH51:

In some embodiments, the host may further include a compound representedby Formula 301 below.

Ar₁₁₁ to Ar₁₁₂ in Formula 301 may be each independently selected from

a phenylene group, a naphthylene group, a phenanthrenylene group, and apyrenylene group; and

a phenylene group, a naphthylene group, a phenanthrenylene group, and apyrenylene group, each substituted with at least one selected from aphenyl group, a naphthyl group, and an anthracenyl group.

Ar₁₁₃ to Ar₁₁₆ in Formula 301 may be each independently selected from aC₁-C₁₀ alkyl group, a phenyl group, a naphthyl group, a phenanthrenylgroup, and a pyrenyl group; and

a phenyl group, a naphthyl group, a phenanthrenyl group, and a pyrenylgroup, each substituted with at least one selected from a phenyl group,a naphthyl group, and an anthracenyl group.

g, h, i, and j in Formula 301 may be each independently an integer of 0to 4, for example, an integer of 0, 1, or 2.

Ar₁₁₃ to Ar₁₁₆ in Formula 301 may be each independently selected from

a C₁-C₁₀ alkyl group substituted with at least one selected from aphenyl group, a naphthyl group, and an anthracenyl group;

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl, aphenanthrenyl group, and a fluorenyl group;

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group,a phenanthrenyl group, and a fluorenyl group, each substituted with atleast one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, acyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, aC₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a phenyl group, a naphthylgroup, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, anda fluorenyl group; and

but embodiments are not limited thereto.

In some embodiments, the host may include a compound represented byFormula 302 below:

Ar₁₂₂ to Ar₁₂₅ in Formula 302 are the same as described in detail inconnection with Ar₁₁₃ in Formula 301.

Ar₁₂₆ and Ar₁₂₇ in Formula 302 may be each independently a C₁-C₁₀ alkylgroup (for example, a methyl group, an ethyl group, or a propyl group).

k and l in Formula 302 may be each independently an integer of 0 to 4.For example, k and l may be 0, 1, or 2.

The compound represented by Formula 301 and the compound represented byFormula 302 may include Compounds H1 to H42 illustrated below, but arenot limited thereto.

When the organic light-emitting device is a full color organiclight-emitting device, the emission layer may be patterned into a redemission layer, a green emission layer, and a blue emission layer. Insome embodiments, due to a stack structure including a red emissionlayer, a green emission layer, and/or a blue emission layer, theemission layer may emit white light.

When the emission layer includes a host and a dopant, an amount of thedopant may be in a range of about 0.01 to about 15 parts by weight basedon 100 parts by weight of the host, but is not limited thereto.

A thickness of the emission layer may be in a range of about 100 Å toabout 1000 Å, for example, about 200 Å to about 600 Å. When thethickness of the emission layer is within this range, excellentlight-emission characteristics may be obtained without a substantialincrease in driving voltage.

Then, an electron transport region may be disposed on the emissionlayer.

The electron transport region may include at least one selected from ahole blocking layer, an electron transport layer, and an electroninjection layer.

For example, the electron transport region may have a structure of holeblocking layer/electron transport layer/electron injection layer or astructure of electron transport layer/electron injection layer, but thestructure of the electron transport region is not limited thereto. Theelectron transport layer may have a single-layered structure or amulti-layer structure including two or more different materials.

Conditions for forming the hole blocking layer, the electron transportlayer, and the electron injection layer which constitute the electrontransport region may be understood by referring to the conditions forforming the hole injection layer.

When the electron transport layer includes a hole blocking layer, thehole blocking layer may include, for example, at least one of BCP,Bphen, and Balq but is not limited thereto.

A thickness of the hole blocking layer may be in a range of about 20 Åto about 1,000 Å, for example, about 30 Å to about 300 Å. When thethickness of the hole blocking layer is within these ranges, the holeblocking layer may have improved hole blocking ability without asubstantial increase in driving voltage.

The electron transport layer may further include at least one selectedfrom BCP, Bphen, Alq₃, BAlq, TAZ, and NTAZ.

In some embodiments, the electron transport layer may include at leastone of ET1 and ET2, but are not limited thereto:

A thickness of the electron transport layer may be in a range of about100 Å to about 1,000 Å, for example, about 150 Å to about 500 Å. Whenthe thickness of the electron transport layer is within the rangedescribed above, the electron transport layer may have satisfactoryelectron transport characteristics without a substantial increase indriving voltage.

Also, the electron transport layer may further include, in addition tothe materials described above, a metal-containing material.

The metal-containing material may include a Li complex. The Li complexmay include, for example, Compound ET-D1 (lithium quinolate, LiQ) orET-D2.

The electron transport region may include an electron injection layer(EIL) that allows electrons to be easily provided from a secondelectrode 19.

The electron injection layer may include at least one selected from,LiF, NaCl, CsF, Li₂O, BaO, and LiQ.

A thickness of the electron injection layer may be in a range of about 1Å to about 100 Å, about 3 Å to about 90 Å. When the thickness of theelectron injection layer is within the range described above, theelectron injection layer may have satisfactory electron injectioncharacteristics without a substantial increase in driving voltage.

The second electrode 19 is disposed on the organic layer 15. The secondelectrode 19 may be a cathode. A material for forming the secondelectrode 19 may be selected from metal, an alloy, an electricallyconductive compound, and a combination thereof, which have a relativelylow work function. For example, lithium (Li), magnesium (Mg), aluminum(Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In),or magnesium-silver (Mg—Ag) may be used as a material for forming thesecond electrode 19. In some embodiments, to manufacture a top emissiontype light-emitting device, a transmissive electrode formed using ITO orIZO may be used as the second electrode 19.

Hereinbefore, the organic light-emitting device has been described withreference to FIG. 1, but is not limited thereto.

A C₁-C₆₀ alkyl group as used herein refers to a linear or branchedaliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms.Detailed examples thereof are a methyl group, an ethyl group, a propylgroup, an isobutyl group, a sec-butyl group, a tert-butyl group, apentyl group, an iso-amyl group, and a hexyl group. A C₁-C₆₀ alkylenegroup as used herein refers to a divalent group having the samestructure as the C₁-C₆₀ alkyl group.

A C₁-C₆₀ alkoxy group as used herein refers to a monovalent grouprepresented by —OA₁₀₁ (wherein A₁₀₁ is the C₁-C₆₀ alkyl group). Detailedexamples thereof are a methoxy group, an ethoxy group, and anisopropyloxy group.

A C₂-C₆₀ alkenyl group as used herein refers to a hydrocarbon grouphaving at least one carbon-carbon double bond in the middle or at theterminal of the C₂-C₆₀ alkyl group.

Detailed examples thereof are an ethenyl group, a propenyl group, and abutenyl group. A C₂-C₆₀ alkenylene group as used herein refers to adivalent group having the same structure as the C₂-C₆₀ alkenyl group.

A C₂-C₆₀ alkynyl group as used herein refers to a hydrocarbon grouphaving at least one carbon-carbon triple bond in the middle or at theterminal of the C₂-C₆₀ alkyl group. Detailed examples thereof are anethynyl group, and a propynyl group. A C₂-C₆₀ alkynylene group as usedherein refers to a divalent group having the same structure as theC₂-C₆₀ alkynyl group.

A C₃-C₁₀ cycloalkyl group as used herein refers to a monovalenthydrocarbon monocyclic group having 3 to 10 carbon atoms. Detailedexamples thereof are a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, and a cycloheptyl group. A C₃-C₁₀cycloalkylene group as used herein refers to a divalent group having thesame structure as the C₃-C₁₀ cycloalkyl group.

A C₁-C₁₀ heterocycloalkyl group as used herein refers to a monovalentmonocyclic group having at least one hetero atom selected from N, O, P,and S as a ring-forming atom and 1 to 10 carbon atoms. Detailed examplesthereof are a tetrahydrofuranyl group, and a tetrahydrothiophenyl group.A C₁-C₁₀ heterocycloalkylene group as used herein refers to a divalentgroup having the same structure as the C₁-C₁₀ heterocycloalkyl group.

A C₃-C₁₀ cycloalkenyl group as used herein refers to a monovalentmonocyclic group that has 3 to 10 carbon atoms and at least one doublebond in the ring thereof, and which is not aromatic. Detailed examplesthereof are a cyclopentenyl group, a cyclohexenyl group, and acycloheptenyl group. A C₃-C₁₀ cycloalkenylene group as used hereinrefers to a divalent group having the same structure as the C₃-C₁₀cycloalkenyl group.

A C₁-C₁₀ heterocycloalkenyl group as used herein refers to a monovalentmonocyclic group that has at least one hetero atom selected from N, O,P, and S as a ring-forming atom, 1 to 10 carbon atoms, and at least onedouble bond in its ring. Detailed examples of the C₁-C₁₀heterocycloalkenyl group are a 2,3-dihydrofuranyl group and a2,3-dihydrothiophenyl group. A C₁-C₁₀ heterocycloalkenylene group asused herein refers to a divalent group having the same structure as theC₁-C₁₀ heterocycloalkenyl group.

A C₆-C₆₀ aryl group as used herein refers to a monovalent group having acarbocyclic aromatic system having 6 to 60 carbon atoms, and a C₆-C₆₀arylene group as used herein refers to a divalent group having acarbocyclic aromatic system having 6 to 60 carbon atoms. Detailedexamples of the C₆-C₆₀ aryl group are a phenyl group, a naphthyl group,an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and achrysenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀ arylene groupeach include two or more rings, the rings may be fused to each other.

A C₁-C₆₀ heteroaryl group as used herein refers to a monovalent grouphaving a carbocyclic aromatic system that has at least one hetero atomselected from N, O, P, and S as a ring-forming atom, and 1 to 60 carbonatoms. A C₁-C₆₀ heteroarylene group as used herein refers to a divalentgroup having a carbocyclic aromatic system that has at least one heteroatom selected from N, O, P, and S as a ring-forming atom, and 1 to 60carbon atoms. Examples of the C₁-C₆₀ heteroaryl group are a pyridinylgroup, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, atriazinyl group, a quinolinyl group, and an isoquinolinyl group. Whenthe C₁-C₆₀ heteroaryl group and the C₁-C₆₀ heteroarylene group eachinclude two or more rings, the rings may be fused to each other.

A C₆-C₆₀ aryloxy group as used herein indicates —OA₁₀₂ (wherein A₁₀₂ isthe C₆-C₆₀ aryl group), and a C₆-C₆₀ arylthio group as used hereinindicates —SA₁₀₃ (wherein A₁₀₃ is the C₆-C₆₀ aryl group).

A monovalent non-aromatic condensed polycyclic group as used hereinrefers to a monovalent group (for example, having 8 to 60 carbon atoms)that has two or more rings condensed to each other, only carbon atoms asa ring forming atom, and which is non-aromatic in the entire molecularstructure. A detailed example of the monovalent non-aromatic condensedpolycyclic group is a fluorenyl group. A divalent non-aromatic condensedpolycyclic group as used herein refers to a divalent group having thesame structure as the monovalent non-aromatic condensed polycyclicgroup.

A monovalent non-aromatic condensed heteropolycyclic group as usedherein refers to a monovalent group (for example, having 2 to 60 carbonatoms) that has two or more rings condensed to each other, has aheteroatom selected from N, O P, and S, other than carbon atoms, as aring forming atom, and which is non-aromatic in the entire molecularstructure. An example of the monovalent non-aromatic condensedheteropolycyclic group is a carbazolyl group. A divalent non-aromaticcondensed heteropolycyclic group as used herein refers to a divalentgroup having the same structure as the monovalent non-aromatic condensedheteropolycyclic group.

At least one of substituents of the substituted C₁-C₆₀ alkyl group,substituted C₂-C₆₀ alkenyl group, substituted C₂-C₆₀ alkynyl group,substituted C₁-C₆₀ alkoxy group, substituted C₃-C₁₀ cycloalkyl group,substituted C₁-C₁₀ heterocycloalkyl group, substituted C₃-C₁₀cycloalkenyl group, substituted C₁-C₁₀ heterocycloalkenyl group,substituted C₆-C₆₀ aryl group, substituted C₆-C₆₀ aryloxy group,substituted C₆-C₆₀ arylthio group, substituted C₁-C₆₀ heteroaryl group,substituted monovalent non-aromatic condensed polycyclic group, andsubstituted monovalent non-aromatic condensed heteropolycyclic group isselected from

a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenylgroup, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group,and a C₁-C₆₀ alkoxy group, each substituted with at least one selectedfrom a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,—CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group,an amidino group, a hydrazine group, a hydrazone group, a carboxylicacid group or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, aC₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),—B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉);

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group;

a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynylgroup, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉); and

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and —P(═O)(Q₃₈)(Q₃₉);

wherein Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ may be eachindependently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroarylgroup, a substituted or unsubstituted monovalent non-aromatic condensedpolycyclic group, and a substituted or unsubstituted monovalentnon-aromatic condensed heteropolycyclic group.

Hereinafter, a compound and an organic light-emitting device accordingto embodiments are described in detail with reference to SynthesisExample and Examples. However, the organic light-emitting device is notlimited thereto. The wording “B was used instead of A” used indescribing Synthesis Examples means that an amount of A used wasidentical to an amount of B used, in terms of a molar equivalent.

EXAMPLE Synthesis Example 1 Synthesis of Compound 1

Synthesis of Compound A1

210 milliliters (mL) of tetrahydrofuran (THF) and 70 mL of distilledwater were mixed with 2-bromo-5-(trimethylsilyl)pyridine (9 grams (g),39.09 millimoles (mmol)),2-(dibenzo[b,d]furan-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane(13.22 g, 44.96 mmol), Pd(PPh₃)₄ (2.26 g, 1.95 mmol), and K₂CO₃ (16.21g, 117.27 mmol). The resultant mixture was stirred under reflux for 18hours. The temperature was decreased to room temperature. The productwas extracted by using methylene chloride (MC). The organic layer wasdried with anhydrous magnesium sulfate (MgSO₄) and the solution wasfiltered. The obtained filtrate was concentrated and the obtainedresidual was purified by column chromatography (MC:Hexane=1:1) to obtain7.4 g (60%) of Compound A1.

Synthesis of Compound M2A

2-phenylpyridine (14.66 g, 94.44 mmol) and iridium chloride (14.80 g,41.97 mmol) were mixed with 210 mL of ethoxyethanol and 70 mL ofdistilled water. The mixture was stirred under reflux for 24 hours tocarry out the reaction. Upon completion of the reaction, the temperaturewas reduced to room temperature. The resultant solid was separated byfiltration and thoroughly washed with water, methanol, and hexane in thestated order. The obtained solid was dried in a vacuum oven to obtain19.5 g (87%) of Compound M2A.

Synthesis of Compound M1A

Compound M2A (6.01 g, 5.60 mmol) was mixed with 45 mL of MC, and asolution of AgOTf (2.88 g, 11.21 mmol) in 15 mL of methanol was addedthereto. The flask was wrapped with an aluminum foil to block thesunlight, and the mixture was stirred at room temperature for 18 hoursto carry out the reaction. The generated solid was removed by celitefiltration, and a filtrate was concentrated under reduced pressure. Theobtained solid (Compound M1A) was used for the subsequent reactionwithout purification.

Synthesis of Compound 1

Compound M1A (8 g, 11.22 mmol) and Compound A1 (4.28 g, 13.47 mmol) weremixed with 100 mL of ethanol, and the resulting mixture was stirredunder reflux for 18 hours to carry out the reaction. Upon completion ofthe reaction, the temperature was reduced to room temperature. Theresultant mixture was filtered to separate a solid, which was thoroughlywashed with ethanol and hexane. The product was purified by columnchromatography (MC:hexane=40:60) to obtain 2.54 g (28%) of Compound 1.The obtained product was confirmed by Mass Spectroscopy and HPLCanalysis.

HRMS(MALDI) calcd for C₄₂H₃₄IrN₃OSi: m/z 817.2100. Found: 817.2104.

Synthesis Example 2 Synthesis of Compound 3

Synthesis of Compound B1

8.5 g (55%) of Compound B1 was prepared in the same manner as used tosynthesize Compound A1 in Synthesis Example 1, except that2-bromo-5-(trimethylsilyl)pyridine (9 g, 39.09 mmol) and9-phenyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-carbazole(13.47 g, 46.92 mmol) were used instead of2-bromo-5-(trimethylsilyl)pyridine (9 g, 39.09 mmol) and2-(dibenzo[b,d]furan-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane(13.22 g, 44.96 mmol), respectively.

Synthesis of Compound 3

2.4 g (32%) of Compound 3 was obtained in the same manner as used tosynthesize Compound 1 in Synthesis Example 1, except that Compound M1A(6.00 g, 8.42 mmol) and Compound B1 (3.97 g, 10.10 mmol) were usedinstead of Compound M1A(8 g, 11.22 mmol) and Compound A1 (4.28 g, 13.47mmol), respectively. The obtained product was confirmed by MassSpectroscopy and HPLC analysis.

HRMS(MALDI) calcd for C₄₈H₃₉IrN₄Si: m/z 892.2573. Found: 892.2575.

Synthesis Example 3 Synthesis of Compound 8

Synthesis of Compound C3

2,5-dibromo-4-methylpyridine (18.55 g, 73.92 mmol),dibenzo[b,d]furan-2-ylboronic acid (18.81 g, 88.70 mmol), Pd(OAc)₂ (1.66g, 7.39 mmol), PPh₃ (3.88 g, 14.78 mmol), and K₂CO₃ (20.43 g, 147.84mmol) were mixed with 200 mL of acetonitrile and 100 mL of methanol. Theresultant mixture was stirred at a temperature of 50° C. for 18 hours.Upon completion, the reaction mixture was cooled to room temperature andfiltered. The product was extracted with methylene chloride (MC). Thecombined organic extracts were dried over anhydrous magnesium sulfate(MgSO₄) and filtered. A filtrate was subjected to reduced pressure andthe obtained residual was purified by column chromatography(MC:Hx=60:40) to obtain 13.0 g (52%) of Compound C3.

Synthesis of Compound C2

300 mL of THF was added to Compound C3 (12.24 g, 36.20 mmol) and themixture was cooled to a temperature of −78° C. A 1.6 molar (M) solutionof n-BuLi (33.94 mL, 54.30 mmol) was slowly added thereto, and theresulting mixture was stirred at a temperature of −78° C. for 1 hour.TMSCl (6.89 mL, 54.30 mmol) was added thereto, and a reaction wascarried out at a temperature of −78° C. for 1 hour, and then at roomtemperature for 12 hours. The organic layer separated therefrom wasextracted with methylene chloride (MC). and the combined organicextracts were dried with anhydrous magnesium sulfate. The dried solutionwas filtered and the filtrate was concentrated under reduced pressure.The crude product was purified by column chromatography (EA:Hexane=4:96)to obtain 8.0 g (67%) of Compound C2.

Synthesis of Compound 8

2.05 g (29%) of Compound 8 was prepared in the same manner as Compound 1in Synthesis Example 1, except that Compound M1A (6.00 g, 8.42 mmol) andCompound C2 (3.35 g, 10.11 mmol) were used instead of Compound M1A (8 g,11.22 mmol) and Compound A1 (4.46 g, 13.47 mmol), respectively. Theobtained product was confirmed by Mass Spectroscopy and HPLC analysis.

HRMS(MALDI) calcd for C₄₃H₃₆IrN₃OSi: m/z 831.2257. Found: 831.2259.

Synthesis Example 4 Synthesis of Compound 22

Synthesis of Compound C1

Compound C2 (7.1 g, 21.42 mmol) was mixed with 100 mL of THF, and theresulting mixture was cooled to a temperature of −78° C. Lithiumdiisopropylamide (LDA, 26.8 mL, 53.54 mmol) was slowly added thereto.The resulting mixture was stirred at a temperature of −78° C. for 1 hourand at room temperature for 1.5 hours to perform the reaction. Thetemperature was reduced to −78° C. 2-bromopropane (5.03 mL, 53.54 mmol)was slowly added to the resulting mixture, the reaction mixture waswarmed to room temperature, and the reaction was carried out for 12hours. The product was extracted with MC. The combined organic extractswere dried over anhydrous magnesium sulfate. The dried organic solutionwas filtered and a filtrate was concentrated under reduced pressure. Theproduct was purified by column chromatography (EA:Hexane=4:96) to obtain6.80 g (85%) of Compound C1.

Synthesis of Compound 22

2.30 g (31%) of Compound 22 was prepared in the same manner as Compound1 in Synthesis Example 1, except that Compound M1A (6.00 g, 8.42 mmol)and Compound C1 (3.77 g, 10.10 mmol) were used instead of Compound M1A(8 g, 11.22 mmol) and Compound A1 (4.28 g, 13.47 mmol), respectively.The obtained product was confirmed by Mass Spectroscopy and HPLCanalysis.

HRMS(MALDI) calcd for C₄₆H₄₂IrN₃OSi: m/z 873.2726. Found: 873.2720.

Synthesis Example 5 Synthesis of Compound 35

Synthesis of Compound D3

13.7 g (69%) of Compound D3 was prepared in the same manner as CompoundC3 of Synthesis Example 3, except that 2,5-dibromo-4-phenylpyridine(15.64 g, 49.97 mmol) and dibenzo[b,d]furan-2-ylboronic acid (12.71 g,55.96 mmol) were used instead of 2,5-dibromo-4-methylpyridine (18.55 g,73.92 mmol) and dibenzo[b,d]furan-2-ylboronic acid (18.81 g, 88.70mmol), respectively.

Synthesis of Compound D2

6.6 g (66%) of Compound D2 was prepared in the same manner as CompoundC2 in Synthesis Example 3, except that Compound D3 (10.17 g, 25.41 mmol)was used instead of Compound C3 (12.24 g, 36.20 mmol).

Synthesis of Compound 35

1.8 g (24%) of Compound 35 was prepared in the same manner as Compound 1in Synthesis Example 1, except that Compound M1A (6.00 g, 8.41 mmol) andCompound D2 (3.97 g, 10.09 mmol) were used instead of Compound M1A (8 g,11.22 mmol) and Compound A1 (4.46 g, 13.47 mmol), respectively. Theobtained product was confirmed by Mass Spectroscopy and HPLC analysis.

HRMS(MALDI) calcd for C₄₈H₃₈IrN₃OSi: m/z 893.2413. Found: 893.2417.

Synthesis Example 6 Synthesis of Compound 300

Synthesis of Compound M2B

17.2 g (86%) of Compound M2B was prepared in the same manner as CompoundM2A in Synthesis Example 1, except that2-phenyl-5-(trimethylsilyl)pyridine (15.05 g, 66.14 mmol) and iridiumchloride (4.10 g, 11.62 mmol) were respectively used instead of2-phenylpyridine (14.66 g, 94.44 mmol) and iridium chloride (14.80 g,41.97 mmol).

Synthesis of Compound M1B

Compound M1B was prepared in the same manner as Compound M1A inSynthesis Example 1, except that Compound M2B (4.76 g, 3.5 mmol) wasused instead of Compound M2A (6.01 g, 5.60 mmol).

Synthesis of Compound 300

1.3 g (19%) of Compound 300 was prepared in the same manner as Compound1 in Synthesis Example 1, except that Compound M1B (6.00 g, 6.99 mmol)and Compound A1 (2.66 g, 8.39 mmol) were used instead of Compound M1A (8g, 11.22 mmol) and Compound A1 (4.46 g, 13.47 mmol), respectively. Theobtained product was confirmed by Mass Spectroscopy and HPLC analysis.

HRMS(MALDI) calcd for C₄₈H₅₀IrN₃OSi₃: m/z 961.2891. Found: 961.2887.

Synthesis Example 7 Synthesis of Compound 305

1.4 g (20%) of Compound 305 was prepared in the same manner as Compound1 in Synthesis Example 1, except that Compound M1B (6.00 g, 6.99 mmol)and Compound C1 (3.14 g, 8.39 mmol) were used instead of Compound MIA (8g, 11.22 mmol) and Compound A1 (4.46 g, 13.47 mmol), respectively. Theobtained product was confirmed by Mass Spectroscopy and HPLC analysis.

HRMS(MALDI) calcd for C₅₂H₅₈IrN₃OSi₃: m/z 1017.3517. Found: 1017.3512.

Synthesis Example 8 Synthesis of Compound 322

1.1 g (16%) of Compound 322 was prepared in the same manner as used tosynthesize Compound 1 in Synthesis Example 1, except that Compound M1B(6.00 g, 6.99 mmol) and Compound E1 (2.78 g, 8.74 mmol) were usedinstead of Compound M1A (8 g, 11.22 mmol) and Compound A1 (4.46 g, 13.47mmol), respectively. The obtained product was confirmed by MassSpectroscopy and HPLC analysis.

HRMS(MALDI) calcd for C₄₇H₄₉IrN₄OSi₃: m/z 962.2843. Found: 962.2843.

Synthesis Example 9 Synthesis of Compound 327

Synthesis of Compound M2C

8.3 g (83%) of Compound M2C was prepared in the same manner as CompoundM2A in Synthesis Example 1, except that Compound A1 (8.3 g, 26.15 mmol)and iridium chloride (4.10 g, 11.62 mmol) were used instead of2-phenylpyridine (14.66 g, 94.44 mmol) and iridium chloride (14.80 g,41.97 mmol), respectively.

Synthesis of Compound M1C

Compound M1C was prepared in the same manner as Compound M1A inSynthesis Example 1, except that Compound M2C (4.973 g, 2.89 mmol) wasused instead of Compound M2A (6.01 g, 5.60 mmol).

Synthesis of Compound 293

1.4 g (25%) of Compound 327 was prepared in the same manner as Compound1 in Synthesis Example 1, except that Compound M1C (6.00 g, 5.78 mmol)and phenylpyridine (1.08 g, 6.94 mmol) were used instead of Compound M1A(8 g, 11.22 mmol) and Compound A1 (4.46 g, 13.47 mmol), respectively.The obtained product was confirmed by Mass Spectroscopy and HPLCanalysis.

HRMS(MALDI) calcd for C₅₁H₄₄IrN₃O₂Si₂: m/z 979.2601. Found: 979.2603.

Example 1

An ITO glass substrate was cut to a size of 50 millimeters (mm)×50mm×0.5 mm, sonicated in acetone, isopropyl alcohol, and pure water, for15 minutes in each solvent, and washed by exposure to UV ozone for 30minutes.

Subsequently, on the ITO electrode (anode) on the glass substrate,m-MTDATA was deposited at a deposition speed of 1 Å/sec to form a holeinjection layer having a thickness of 600 Å, and α-NPD was deposited onthe hole injection layer at a deposition rate of 1 Å/sec to form a holetransport layer having a thickness of 250 Å.

Compound 1 (dopant) and CBP (host) were co-deposited on the holetransport layer at a deposition rate of 0.1 Å/sec and a deposition rateof 1 Å/sec, respectively, to form an emission layer having a thicknessof 400 Å.

BAlq was deposited on the emission layer at a deposition rate of 1 Å/secto form a hole blocking layer having a thickness of 50 Å, and Alq₃ wasdeposited on the hole blocking layer to form an electron transport layerhaving a thickness of 300 Å. Subsequently, LiF was deposited on theelectron transport layer to form an electron injection layer having athickness of 10 Å, and Al was vacuum deposited on the electron injectionlayer to form a second electrode (cathode) having a thickness of 1,200Å, thereby completing the manufacture of an organic light-emittingdevice having a structure of ITO/m-MTDATA (600 Å)/α-NPD (250 Å)/CBP+10%(Compound 1) (400 Å)/BAlq (50 Å) /Alq₃ (300 Å)/LiF (10 Å) /Al (1,200 Å).

Examples 2 to 9 and Comparative Example 1

Organic light-emitting devices were manufactured in the same manner asin Example 1, except that in forming an emission layer, correspondingcompounds shown in Table 2 were used as a dopant instead of Compound 1.

Evaluation Example 1 Evaluation on Characteristics of OrganicLight-Emitting Devices

The driving voltage, efficiency, power, color purity, and lifespan (T₉₅)of the organic light-emitting devices manufactured according to Examples1 to 9 and Comparative Example 1 were evaluated. Results thereof areshown in Table 2. This evaluation was performed using a current-voltagemeter (Keithley 2400) and a luminance meter (Minolta Cs-1000A), and thelifespan (T₉₅) (at 6000 nit) was evaluated by measuring the amount oftime that elapsed until luminance was reduced to 95% of the initialbrightness of 100%.

TABLE 2 Driv- ing Life- Vol- Effi- span tage ciency Power (hr) Dopant(V) (cd/A) (lm/W) CIEx CIEy (T₉₅) Example 1 Compound 1 5.0 49.0 30.80.339 0.605 210 Example 2 Compound 3 4.8 47.5 31.1 0.340 0.602 145Example 3 Compound 8 4.9 48.0 30.8 0.338 0.607 195 Example 4 Compound 225.0 48.5 30.5 0.336 0.604 200 Example 5 Compound 35 5.2 50.5 30.5 0.3560.605 230 Example 6 Compound 300 4.8 51.0 33.4 0.360 0.607 230 Example 7Compound 305 4.9 50.0 32.0 0.345 0.605 210 Example 8 Compound 322 4.951.5 33.0 0.355 0.604 150 Example 9 Compound 327 4.6 50.5 34.5 0.3400.607 180 Compara- Compound A 5.1 47.5 29.2 0.340 0.607  85 tive Example1

Referring to Table 2, it was confirmed that the organic light-emittingdevices manufactured according to Examples 1 to 9 have a lower drivingvoltage, higher efficiency, higher power, higher color purity, and alonger lifespan, than the organic light-emitting devices manufacturedaccording to Comparative Example 1.

The organometallic compound according to embodiments has excellentelectric characteristics and thermal stability. Accordingly, an organiclight-emitting device including the organometallic compound may haveexcellent driving voltage, efficiency, power, color purity, and lifespancharacteristics.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each exemplaryembodiment should typically be considered as available for other similarfeatures or aspects in other exemplary embodiments.

While one or more exemplary embodiments have been described withreference to the FIGURES, it will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinventive concept as defined by the following claims.

What is claimed is:
 1. An organometallic compound represented by Formula1:

wherein M in Formula 1 is selected from Ir, Pt, Os, Ti, Zr, Hf, Eu, Tb,Tm, and Rh, in Formula 1, L₁ is a ligand represented by Formula 2A, n1is 1, 2, or 3, and when n1 is 2 or more, 2 or more L₁ are identical ordifferent, in Formula 1, L₂ is selected from a monovalent organicligand, a divalent organic ligand, a trivalent organic ligand, and atetravalent organic ligand, n2 is 0, 1, 2, 3, or 4, and when n2 is 2 ormore, 2 or more L₂ are identical or different, L₁ and L₂ in Formula 1are different from each other, R₁ to R₃ in Formula 2A are eachindependently selected from a substituted or unsubstituted C₁-C₆₀ alkylgroup, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalentnon-aromatic condensed polycyclic group, a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group, and—Si(Q₅₁)(Q₅₂)(Q₅₃), X₁ in Formula 2A is selected from O, S, S(═O)₂,N(R₂₁), and Si(R₂₂)(R₂₃), in Formula 2A, Y₁ is N, C(R₄₁), or a carbonatom connected to a pyridine ring, Y₂ is N, C(R₄₂), or a carbon atomconnected to a pyridine ring, Y₃ is N, C(R₄₃), or a carbon atomconnected to a pyridine ring, Y₄ is N, C(R₄₄), or a carbon atomconnected to a pyridine ring, Y₅ is N or C(R₄₅), Y₆ is N or C(R₄₆), Y₇is N or C(R₄₇), Y₈ is N or C(R₄₈), and one of Y₁ to Y₄ is a carbon atomconnected to a pyridine ring, R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula2A are each independently selected from a hydrogen, a deuterium, —F,—Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, anamino group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a substituted orunsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, asubstituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₆-C₆₀ aryloxy group, asubstituted or unsubstituted C₆-C₆₀ arylthio group, a substituted orunsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstitutedmonovalent non-aromatic condensed polycyclic group, a substituted orunsubstituted monovalent non-aromatic condensed heteropolycyclic group,—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), and 2 ormore R₁₁ optionally are linked to each other to form a saturated orunsaturated C₄-C₆₀ ring, two or more of R₄₁ to R₄₄ are optionally linkedto each other to form a saturated or unsaturated C₄-C₆₀ ring, and two ormore of R₄₅ to R₄₈ are optionally linked to each other to form asaturated or unsaturated C₄-C₆₀ ring, in Formula 2A, b1 is an integerselected from 0 to 3, and b4 is an integer selected from 1 to 4, * and*′ in Formula 2A are binding sites to M in Formula 1, at least one ofsubstituents of the substituted C₁-C₆₀ alkyl group, substituted C₂-C₆₀alkenyl group, substituted C₂-C₆₀ alkynyl group, substituted C₁-C₆₀alkoxy group, substituted C₃-C₁₀ cycloalkyl group, substituted C₁-C₁₀heterocycloalkyl group, substituted C₃-C₁₀ cycloalkenyl group,substituted C₁-C₁₀ heterocycloalkenyl group, substituted C₆-C₆₀ arylgroup, substituted C₆-C₆₀ aryloxy group, substituted C₆-C₆₀ arylthiogroup, substituted C₁-C₆₀ heteroaryl group, substituted monovalentnon-aromatic condensed polycyclic group, and substituted monovalentnon-aromatic condensed heteropolycyclic group is selected from adeuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenylgroup, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group; a C₁-C₆₀ alkylgroup, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀alkoxy group, each substituted with at least one selected from adeuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),—B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉); a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, and a monovalent non-aromaticcondensed heteropolycyclic group; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, and a monovalent non-aromaticcondensed heteropolycyclic group, each substituted with at least oneselected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an aminogroup, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkylgroup, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxygroup, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, aC₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,a monovalent non-aromatic condensed heteropolycyclic group,—N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉);and —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and—P(═O)(Q₃₈)(Q₃₉); wherein Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, Q₃₁ to Q₃₉and Q₅₁ to Q₅₃ are each independently selected from a hydrogen, adeuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, asubstituted or unsubstituted C₁-C₆₀ alkyl group, a substituted orunsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstitutedC₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxygroup, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, asubstituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted orunsubstituted monovalent non-aromatic condensed polycyclic group, and asubstituted or unsubstituted monovalent non-aromatic condensedheteropolycyclic group.
 2. The organometallic compound of claim 1,wherein in Formula 1, M is Ir and the sum of n1 and n2 is 3; or M is Ptand the sum of n1 and n2 is 2, and the organometallic compound does notcomprise an ionic group.
 3. The organometallic compound of claim 1,wherein R₁ to R₃ in Formula 2A are each independently selected from aC₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, and —Si(Q₅₁)(Q₅₂)(Q₅₃); aC₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted with atleast one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, an adamantanyl group, norbornanyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group; a cyclopentyl group, a cyclohexyl group,a cycloheptyl group, a cyclooctyl group, an adamantanyl group,norbornanyl group, a norbornenyl group, a cyclopentenyl group, acyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthylgroup, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, afluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenylgroup, a pyrrolyl group, a thiophenyl group, a furanyl group, animidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolylgroup, an oxazolyl group, an isoxazolyl group, a pyridinyl group, apyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolylgroup, an indolyl group, an indazolyl group, a purinyl group, aquinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, aquinoxalinyl group, a quinazolinyl group, a cinnolinyl group, acarbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, abenzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group,a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, atetrazolyl group, an oxadiazolyl group, a triazinyl group, adibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group; and a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantanyl group, norbornanylgroup, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, abenzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinylgroup, and an imidazopyrimidinyl group; and Q₅₁ to Q₅₃ are eachindependently selected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃,—CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃,—CD₂CD₂H, and —CD₂CDH₂; an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, a phenyl group, and a naphthyl group; and an n-propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group,a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, a phenyl group, and a naphthyl group, eachsubstituted with at least one selected from a deuterium, a C₁-C₁₀ alkylgroup, and a phenyl group.
 4. The organometallic compound of claim 1,wherein R₁ to R₃ in Formula 2A are each independently selected from—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃,—CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂; ann-propyl group, an isopropyl group, an n-butyl group, an isobutyl group,a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentylgroup, a sec-pentyl group, a tert-pentyl group, a phenyl group, anaphthyl group, and —Si(Q₅₁)(Q₅₂)(Q₅₃); and an n-propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group,a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, a phenyl group, and a naphthyl group, eachsubstituted with at least one selected from a deuterium, a C₁-C₁₀ alkylgroup, and a phenyl group; and Q₅₁ to Q₅₃ are each independentlyselected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H,—CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and—CD₂CDH₂; an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, an isopentyl group, a sec-pentyl group, a tert-pentyl group, aphenyl group, and a naphthyl group; and an n-propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a sec-butyl group, atert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, a phenyl group, and a naphthyl group, eachsubstituted with at least one selected from a deuterium, a C₁-C₁₀ alkylgroup, and a phenyl group.
 5. The organometallic compound of claim 1,wherein R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A are eachindependently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I,—SF₅, a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, and aC₁-C₂₀ alkoxy group; a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group,each substituted with at least one selected from a deuterium, —F, —Cl,—Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, acyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, aC₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₁₄ arylgroup, a C₁-C₁₄ heteroaryl group, a monovalent non-aromatic condensedpolycyclic group, and a monovalent non-aromatic condensedheteropolycyclic group; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₁₄ aryl group, a C₁-C₁₄ heteroarylgroup, a monovalent non-aromatic condensed polycyclic group, and amonovalent non-aromatic condensed heteropolycyclic group; a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₁₄ aryl group, a C₁-C₁₄heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₁₄ aryl group, a C₁-C₁₄heteroaryl group, a monovalent non-aromatic condensed polycyclic group,and a monovalent non-aromatic condensed heteropolycyclic group; and—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉); wherein Q₁to Q₉ are each independently selected from a substituted orunsubstituted C₁-C₂₀ alkyl group, a substituted or unsubstituted C₁-C₂₀alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₁₄ aryl group, a substituted or unsubstituted C₁-C₁₄heteroaryl group, a substituted or unsubstituted monovalent non-aromaticcondensed polycyclic group, and a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group.
 6. Theorganometallic compound of claim 1, wherein R₁₁, R₂₁ to R₂₃ and R₄₁ toR₄₈ in Formula 2A are each independently selected from a hydrogen, adeuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, —SF₅, aC₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxy group; a C₁-C₂₀ alkyl group anda C₁-C₂₀ alkoxy group, each substituted with at least one selected froma deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amino group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₁₀ alkyl group, a cyclopentyl group,a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup; a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclooctyl group, an adamantanyl group, norbornanyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a phenyl group, a naphthyl group, a fluorenyl group, aphenanthrenyl group, an anthracenyl group, a fluoranthenyl group, atriphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolylgroup, a thiophenyl group, a furanyl group, an imidazolyl group, apyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolylgroup, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, apyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolylgroup, an indazolyl group, a purinyl group, a quinolinyl group, anisoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group; acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, abenzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinylgroup, and an imidazopyrimidinyl group, each substituted with at leastone selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂,—CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, anamino group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkylgroup, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantanyl group, norbornanylgroup, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group; and—B(Q₆)(Q₇) and —P(═O)(Q₈)(Q₉), wherein Q₆ to Q₉ are each independentlyselected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H,—CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and—CD₂CDH₂; an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, an isopentyl group, a sec-pentyl group, a tert-pentyl group, aphenyl group, and a naphthyl group; and an n-propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a sec-butyl group, atert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, a phenyl group, and a naphthyl group, eachsubstituted with at least one selected from a deuterium, a C₁-C₁₀ alkylgroup, and a phenyl group.
 7. The organometallic compound of claim 1,wherein R₁₁, R₂₁ to R₂₃ and R₄₁ to R₄₈ in Formula 2A are eachindependently selected from a hydrogen, a deuterium, —F, a cyano group,a nitro group, —SF₅, a methyl group, an ethyl group, an n-propyl group,an isopropyl group, an n-butyl group, an isobutyl group, a sec-butylgroup, a tert-butyl group, an n-pentyl group, an isopentyl group, asec-pentyl group, a tert-pentyl group, an n-hexyl group, an isohexylgroup, a sec-hexyl group, a tert-hexyl group, an n-heptyl group, anisoheptyl group, a sec-heptyl group, a tert-heptyl group, an n-octylgroup, an isooctyl group, a sec-octyl group, a tert-octyl group, ann-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group,an n-decyl group, an isodecyl group, a sec-decyl group, a tert-decylgroup, a methoxy group, an ethoxy group, a propoxy group, a butoxygroup, a pentoxy group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantanyl, norbornanylgroup, a norbornenyl, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group; a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, an isobutyl group,a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentylgroup, a sec-pentyl group, a tert-pentyl group, an n-hexyl group, anisohexyl group, a sec-hexyl group, a tert-hexyl group, an n-heptylgroup, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, ann-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group,an n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonylgroup, an n-decyl group, an isodecyl group, a sec-decyl group, atert-decyl group, a methoxy group, an ethoxy group, a propoxy group, abutoxy group, a pentoxy group, a cyclopentyl group, a cyclohexyl group,a cycloheptyl group, a cyclooctyl group, an adamantanyl group,norbornanyl group, a norbornenyl group, a cyclopentenyl group, acyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthylgroup, a pyridinyl group, and a pyrimidinyl group, each substituted withat least one selected from a deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a cyano group, a nitro group, a C₁-C₁₀ alkyl group, aC₁-C₁₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantanyl group, norbornanylgroup, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group; and —B(Q₆)(Q₇) and —P(═O)(Q₈)(Q₉),wherein Q₆ to Q₉ are each independently selected from —CH₃, —CD₃, —CD₂H,—CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H,—CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂; an n-propyl group,an isopropyl group, an n-butyl group, an isobutyl group, a sec-butylgroup, a tert-butyl group, an n-pentyl group, an isopentyl group, asec-pentyl group, a tert-pentyl group, a phenyl group, and a naphthylgroup; and an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, an isopentyl group, a sec-pentyl group, a tert-pentyl group, aphenyl group, and a naphthyl group, each substituted with at least oneselected from a deuterium, a C₁-C₁₀ alkyl group, and a phenyl group. 8.The organometallic compound of claim 1, wherein R₁₁, R₂₁ to R₂₃ and R₄₁to R₄₈ in Formula 2A are each independently selected from a hydrogen, adeuterium, —F, a cyano group, a nitro group, —SF₅, —CH₃, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, groups represented by Formulae 9-1 to 9-17,and groups represented by Formulae 10-1 to 10-30:

wherein in Formulae 9-1 to 9-17 and 10-1 to 10-30, * is a binding siteto a neighboring atom.
 9. The organometallic compound of claim 1,wherein two groups R₁₁ in Formula 2A are linked to each other to form asubstituted or unsubstituted cyclohexane or a substituted orunsubstituted benzene.
 10. The organometallic compound of claim 1,wherein L₁ is selected from ligands represented by Formulae 2A-1 to2A-16:

wherein in Formulae 2A-1 to 2A-16, R₁ to R₃, X₁, Y₁ to Y₈, R₁₁, and b1and b4 are the same as defined in claim 1, R₁₅ is the same as R₁₁, b5 isan integer selected from 0 to 8 and * and *′ are binding sites to M inFormula
 1. 11. The organometallic compound of claim 10, wherein inFormulae 2A-1 to 2A-16, Y₁ is C(R₄₁), Y₂ is C(R₄₂), Y₃ is C(R₄₃), Y₄ isC(R₄₄), Y₅ is C(R₄₅), Y₆ is C(R₄₆), Y₇ is C(R₄₇), and Y₈ is C(R₄₈); inFormulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12, 2A-13,2A-14, and 2A-16, Y₁ is N, Y₄ is C(R₄₄), Y₅ is C(R₄₅), Y₆ is C(R₄₆), Y₇is C(R₄₇), and Y₈ is C(R₄₈); in Formulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6,2A-8, 2A-9, 2A-10, 2A-12, 2A-13, 2A-14, and 2A-16, Y₁ is C(R₄₁), Y₄ isC(R₄₄), Y₅ is N, Y₆ is C(R₄₆), Y₇ is C(R₄₇), and Y₈ is C(R₄₈); inFormulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12, 2A-13,2A-14, and 2A-16, Y₁ is C(R₄₁), Y₄ is C(R₄₄), Y₅ is C(R₄₅), Y₆ is N, Y₇is C(R₄₇), and Y₈ is C(R₄₈); in Formulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6,2A-8, 2A-9, 2A-10, 2A-12, 2A-13, 2A-14, and 2A-16, Y₁ is N, Y₄ isC(R₄₄), Y₅ is N, Y₆ is C(R₄₆), Y₇ is C(R₄₇), and Y₈ is C(R₄₈); inFormulae 2A-1, 2A-2, 2A-4, 2A-5, 2A-6, 2A-8, 2A-9, 2A-10, 2A-12, 2A-13,2A-14, and 2A-16, Y₁ is N, Y₄ is C(R₄₄), Y₅ is C(R₄₅), Y₆ is N, Y₇ isC(R₄₇), and Y₈ is C(R₄₈); in Formulae 2A-3, 2A-7, 2A-11, and 2A-15, Y₃is N, Y₄ is C(R₄₄), Y₅ is C(R₄₅), Y₆ is C(R₄₆), Y₇ is C(R₄₇), and Y₈ isC(R₄₈); in Formulae 2A-3, 2A-7, 2A-11, and 2A-15 Y₃ is C(R₄₃), Y₄ isC(R₄₄), Y₅ is N, Y₆ is C(R₄₆), Y₇ is C(R₄₇), and Y₈ is C(R₄₈); inFormulae 2A-3, 2A-7, 2A-11, and 2A-15, Y₃ is C(R₄₃), Y₄ is C(R₄₄), Y₅ isC(R₄₅), Y₆ is N, Y₇ is C(R₄₇), and Y₈ is C(R₄₈); in Formulae 2A-3, 2A-7,2A-11, and 2A-15, Y₃ is N, Y₄ is C(R₄₄), Y₅ is N, Y₆ is C(R₄₆), Y₇ isC(R₄₇), and Y₈ is C(R₄₈); or in Formulae 2A-3, 2A-7, 2A-11, and 2A-15,Y₃ is N, Y₄ is C(R₄₄), Y₅ is C(R₄₅), Y₆ is N, Y₇ is C(R₄₇), and Y₈ isC(R₄₈)
 12. The organometallic compound of claim 1, wherein L₁ in Formula1 is selected from groups represented by Formulae 2AA-1, 2AA-2, 2AA-3,2AA-4, and 2AB below:

in Formulae 2AA-1, 2AA-2, 2AA-3, 2AA-4, and 2AB, R₁ to R₃ are eachindependently selected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃,—CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃,—CD₂CD₂H, and —CD₂CDH₂; an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, a phenyl group, a naphthyl group, and —Si(Q₅₁)(Q₅₂)(Q₅₃); and ann-propyl group, an isopropyl group, an n-butyl group, an isobutyl group,a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentylgroup, a sec-pentyl group, a tert-pentyl group, a phenyl group, and anaphthyl group, each substituted with at least one selected from adeuterium and a C₁-C₁₀ alkyl group, Q₅₁ to Q₅₃ are each independentlyselected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H,—CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, and—CD₂CDH₂; an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, an isopentyl group, a sec-pentyl group, a tert-pentyl group, aphenyl group, and a naphthyl group; and an n-propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a sec-butyl group, atert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, a phenyl group, and a naphthyl group, eachsubstituted with at least one selected from a deuterium, a C₁-C₁₀ alkylgroup, and a phenyl group, X₁ is selected from O, S, S(═O)₂, N(R₂₁), andSi(R₂₂)(R₂₃), descriptions of Y₁ to Y₈ are the same as in claim 1, R₁₁,R₁₅, and R₂₁ to R₂₃ are each independently selected from a hydrogen, adeuterium, —F, a cyano group, a nitro group, —SF₅, a methyl group, anethyl group, an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, an isopentyl group, a sec-pentyl group, a tert-pentyl group, ann-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group,an n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptylgroup, an n-octyl group, an isooctyl group, a sec-octyl group, atert-octyl group, an n-nonyl group, an isononyl group, a sec-nonylgroup, a tert-nonyl group, an n-decyl group, an isodecyl group, asec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl, norbornanyl group, a norbornenyl, a cyclopentenyl group, acyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthylgroup, a pyridinyl group, and a pyrimidinyl group; a methyl group, anethyl group, an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, an isopentyl group, a sec-pentyl group, a tert-pentyl group, ann-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group,an n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptylgroup, an n-octyl group, an isooctyl group, a sec-octyl group, atert-octyl group, an n-nonyl group, an isononyl group, a sec-nonylgroup, a tert-nonyl group, an n-decyl group, an isodecyl group, asec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup, each substituted with at least one selected from a deuterium, —F,—CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, a nitro group, aC₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinylgroup; and —B(Q₆)(Q₇) and —P(═O)(Q₈)(Q₉), wherein Q₆ to Q₉ are eachindependently selected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃,—CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃,—CD₂CD₂H, and —CD₂CDH₂; an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, a phenyl group, and a naphthyl group; and an n-propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group,a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, and a phenyl group, and a naphthyl group,each substituted with at least one selected from a deuterium and aC₁-C₁₀ alkyl group, b5 is an integer selected from 0 to 8, and * and *′are binding sites to M in Formula
 1. 13. The organometallic compound ofclaim 1, wherein L₁ is selected from ligands represented by Formulae2A(1) to 2A(40):

wherein in Formulae 2A(1) to 2A(40), descriptions of R₁ to R₃, X₁, Y₁ toY₈, and R₁ are the same as in claim 1, R_(11a) and R_(11b) areunderstood by referring to the description of R₁₁, provided that R₁₁,R_(11a), and R_(11b) are not hydrogen, and each of * and *′ is a bindingsite to M in Formula
 1. 14. The organometallic compound of claim 1,wherein L₂ in Formula 1 is selected from ligands represented by Formulae3A to 3G:

wherein in Formulae 3A to 3G, Y₁₁ to Y₁₆ are each independently C or N,Y₁₁ and Y₁₂ are linked to each other by a single bond or a double bond,Y₁₃ and Y₁₄ are linked to each other by a single bond or a double bond,and Y₁₅ and Y₁₆ are linked to each other by a single bond or a doublebond, CY₃ to CY₅ are each independently selected from a C₅-C₆₀carbocyclic group and a C₂-C₆₀ heterocyclic group. a1 to a3 are eachindependently an integer selected from 1 to 5; A₁ is P or As; X_(11a),X_(11b), X_(12a), X_(12b), X_(13a), and X_(13b) are each independentlyselected from N, O, N(R₃₄), P(R₃₅)(R₃₆), and As(R₃₇)(R₃₈), provided thatnone of X_(12a), X_(12b), X_(13a), and X_(13b) are N or O; R_(33″) andR_(34″) are each independently selected from a single bond, a doublebond, a substituted or unsubstituted C₁-C₅ alkylene group, a substitutedor unsubstituted C₂-C₅ alkenylene group, and a substituted orunsubstituted C₆-C₁₀ arylene group; Z₁ to Z₃, R₃₁, R_(32a), R_(32b),R_(32c), R_(33a), R_(33b), R₃₄ to R₃₈, R_(35a), R_(35b), R_(35c), andR_(35d) are each independently selected from a hydrogen, a deuterium,—F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, anamino group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a substituted orunsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, asubstituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₆-C₆₀ aryloxy group, asubstituted or unsubstituted C₆-C₆₀ arylthio group, a substituted orunsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstitutedmonovalent non-aromatic condensed polycyclic group, a substituted orunsubstituted monovalent non-aromatic condensed heteropolycyclic group,—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉), * and *′each indicate binding sites to M in Formula 1; at least one ofsubstituents of the substituted C₁-C₅ alkylene group, substituted C₂-C₅alkenylene group, substituted C₆-C₁₀ arylene group, substituted C₁-C₆₀alkyl group, substituted C₂-C₆₀ alkenyl group, substituted C₂-C₆₀alkynyl group, substituted C₁-C₆₀ alkoxy group, substituted C₃-C₁₀cycloalkyl group, substituted C₁-C₁₀ heterocycloalkyl group, substitutedC₃-C₁₀ cycloalkenyl group, substituted C₁-C₁₀ heterocycloalkenyl group,substituted C₆-C₆₀ aryl group, substituted C₆-C₆₀ aryloxy group,substituted C₆-C₆₀ arylthio group, substituted C₁-C₆₀ heteroaryl group,substituted monovalent non-aromatic condensed polycyclic group andsubstituted monovalent non-aromatic condensed heteropolycyclic group isselected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an aminogroup, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkylgroup, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀alkoxy group; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀alkynyl group, and a C₁-C₆₀ alkoxy group, each substituted with at leastone selected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂,—CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, anamino group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkylgroup, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, aC₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxygroup, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),—B(Q₁₆)(Q₁₇), and —P(═O)(Q₁₈)(Q₁₉); a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, and a monovalent non-aromaticcondensed heteropolycyclic group; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalentnon-aromatic condensed polycyclic group, and a monovalent non-aromaticcondensed heteropolycyclic group, each substituted with at least oneselected from a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an aminogroup, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkylgroup, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxygroup, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, aC₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀heteroaryl group, a monovalent non-aromatic condensed polycyclic group,a monovalent non-aromatic condensed heteropolycyclic group,—N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), and —P(═O)(Q₂₈)(Q₂₉);and —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), and—P(═O)(Q₃₈)(Q₃₉); wherein Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ toQ₃₉ are each independently selected from a hydrogen, a deuterium, —F,—Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an aminogroup, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a substituted orunsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, asubstituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₆-C₆₀ aryloxy group, asubstituted or unsubstituted C₆-C₆₀ arylthio group, a substituted orunsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstitutedmonovalent non-aromatic condensed polycyclic group, and a substituted orunsubstituted monovalent non-aromatic condensed heteropolycyclic group.15. The organometallic compound of claim 1, wherein L₂ in Formula 1 isselected from ligands represented by Formulae 3-1 to 3-111:

wherein in Formulae 3-1 to 3-111, Z₁, Z₂, Z_(1a), Z_(1b), Z_(2a),Z_(2b), Z_(2c), R_(34a), R_(34b), and R_(34c) are each independentlyselected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxylgroup, a cyano group, a nitro group, an amino group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, —SF₅, a C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxygroup; a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substitutedwith at least one selected from a deuterium, —F, —Cl, —Br, —I, —CD₃,—CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, anitro group, an amino group, an amidino group, a hydrazine group, ahydrazone group, a carboxylic acid group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantanyl group, norbornanylgroup, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a phenyl group, a naphthyl group, a pyridinylgroup, and a pyrimidinyl group; a cyclopentyl group, a cyclohexyl group,a cycloheptyl group, a cyclooctyl group, an adamantanyl group,norbornanyl group, a norbornenyl group, a cyclopentenyl group, acyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthylgroup, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, afluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenylgroup, a pyrrolyl group, a thiophenyl group, a furanyl group, animidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolylgroup, an oxazolyl group, an isoxazolyl group, a pyridinyl group, apyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolylgroup, an indolyl group, an indazolyl group, a purinyl group, aquinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, aquinoxalinyl group, a quinazolinyl group, a cinnolinyl group, acarbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, abenzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group,a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, atetrazolyl group, an oxadiazolyl group, a triazinyl group, adibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, an imidazopyridinyl group, and animidazopyrimidinyl group; a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantanyl group, norbornanylgroup, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenylgroup, a phenanthrenyl group, an anthracenyl group, a fluoranthenylgroup, a triphenylenyl group, a pyrenyl group, a chrysenyl group, apyrrolyl group, a thiophenyl group, a furanyl group, an imidazolylgroup, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, anoxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinylgroup, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, anindolyl group, an indazolyl group, a purinyl group, a quinolinyl group,an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, aquinazolinyl group, a cinnolinyl group, a carbazolyl group, aphenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, abenzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group,an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, anoxadiazolyl group, a triazinyl group, a dibenzofuranyl group, adibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolylgroup, an imidazopyridinyl group, and an imidazopyrimidinyl group, eachsubstituted with at least one selected from a deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentylgroup, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, anadamantanyl group, norbornanyl group, a norbornenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, aphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenylgroup, an anthracenyl group, a fluoranthenyl group, a triphenylenylgroup, a pyrenyl group, a chrysenyl group, a pyrrolyl group, athiophenyl group, a furanyl group, an imidazolyl group, a pyrazolylgroup, a thiazolyl group, an isothiazolyl group, an oxazolyl group, anisoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinylgroup, a pyridazinyl group, an isoindolyl group, an indolyl group, anindazolyl group, a purinyl group, a quinolinyl group, an isoquinolinylgroup, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinylgroup, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group,a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group,an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, atriazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, abenzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinylgroup, and an imidazopyrimidinyl group; and —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅),—B(Q₆)(Q₇), and —P(═O)(Q₈)(Q₉); Q₁ to Q₉ and Q₄₄ to Q₄₉ are eachindependently selected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃,—CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃,—CD₂CD₂H, and —CD₂CDH₂; an n-propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group,an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentylgroup, a phenyl group, and a naphthyl group; and an n-propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group,a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, and a phenyl group, and a naphthyl group,each substituted with at least one selected from a deuterium and aC₁-C₁₀ alkyl group, aa2 and ab2 are each independently 1 or 2, aa3 andab3 are each independently selected from 1, 2, and 3, aa4 and ab4 areeach independently selected from, 1, 2, 3, and 4, and * and *′ eachindicate binding sites to M in Formula
 1. 16. The organometalliccompound of claim 1, wherein L₂ in Formula 1 is selected from ligandsrepresented by Formulae 3-1 (1) to 3-1(59), and 3-111:

wherein in Formulae 3-1(1) to 3-1(59) and Formula 3-111: Z₁, Z₂, Z_(1a),Z_(1b), Z_(1c), Z_(1d), Z_(2a), Z_(2b), Z_(2c), Z_(2d), R_(34a),R_(34b), and R_(34c) are each independently selected from a deuterium,—F, a cyano group, a nitro group, —SF₅, —CH₃, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, —Si(Q₃)(Q₄)(Q₅), groups represented by Formulae 9-1 to9-17, and groups represented by Formulae 10-1 to 10-30, Q₃ to Q₅ areeach independently selected from —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃,—CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃,—CD₂CD₃, —CD₂CD₂H, and —CD₂CDH₂; an n-propyl group, an isopropyl group,an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, an n-pentyl group, an isopentyl group, a sec-pentyl group, atert-pentyl group, a phenyl group, and a naphthyl group; and an n-propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, asec-butyl group, a tert-butyl group, an n-pentyl group, an isopentylgroup, a sec-pentyl group, a tert-pentyl group, and a phenyl group, eachsubstituted with at least one selected from a deuterium and a C₁-C₁₀alkyl group, and * and *′ are binding sites to M in Formula 1,

wherein in Formulae 9-1 to 9-17 and 10-1 to 10-30, * is a binding siteto a neighboring atom.
 17. The organometallic compound of claim 1,wherein the organometallic compound is one of Compounds 1 to 481:


18. An organic light-emitting device comprising: a first electrode; asecond electrode; and an organic layer disposed between the firstelectrode and the second electrode, wherein the organic layer comprisesan emission layer and at least one organometallic compound of claim 1.19. The organic light-emitting device of claim 18, wherein the firstelectrode is an anode, the second electrode is a cathode, and theorganic layer comprises a hole transport region between the firstelectrode and the emission layer, and an electron transport regionbetween the emission layer and the second electrode, wherein the holetransport region comprises at least one of a hole injection layer, ahole transport layer, and an electron blocking layer and the electrontransport region comprises at least one selected from a hole blockinglayer, an electron transport layer, and an electron injection layer. 20.The organic light-emitting device of claim 18, wherein the emissionlayer comprises at least one organometallic compound of claim 1.